Co-reporter:Shenglong Shang, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Journal of Colloid and Interface Science 2017 Volume 485() pp:18-24
Publication Date(Web):1 January 2017
DOI:10.1016/j.jcis.2016.09.016
A flexible, magnetic field induced structurally colored films with brilliant colors and high physical rigidity were reported in this article. Using an external magnetic field, the photocurable colloidal suspensions that containing superparamagnetic Fe3O4@C colloidal nanocrystal clusters (CNCs) could polymerize under UV light. After polymerization, the films with different colors (red, green, blue) were obtained. Through combination of suspensions which contains Fe3O4@C CNCs with different sizes, a series of multi-colored films were obtained. Moreover, these structural colors can be patterned easily by photolithography and various structural colored patterns were shown in the article. The structural colored patterns could conceal or display its color according to the changing of background which makes them hold significant potential applications for security materials.A new type of structural colored patterns which display colors depending on the background are used for security materials.
Co-reporter:Yaoqing Chu, Qinghong Zhang, Yaogang Li, Zhifu Liu, Jiayue Xu, Haibo Zeng, Hongzhi Wang
Journal of Alloys and Compounds 2017 Volume 693() pp:308-314
Publication Date(Web):5 February 2017
DOI:10.1016/j.jallcom.2016.09.115
•Eu3+-activated Bi4Ge3O12 red phosphors were synthesized by a simple method.•The growth process of the phosphor was recorded by SEM.•The phosphors had good thermal stability from room temperature to 498 K.•This phosphor matched well with the output wavelength of commercial near-UV LED chips and blue LED chips.Eu3+-activated bismuth germanate (Bi4Ge3O12:Eu3+), as an alternative to commercial red phosphors, were synthesized by a hydrothermal method with different doping concentrations. The growth process of the Bi4Ge3O12:Eu3+ phosphor was recorded by SEM. The as-prepared Bi4Ge3O12:Eu3+ phosphors showed strong red emission at 612 nm corresponding to the 5D0→7F2 transition of Eu3+ under excitation of 394 nm. The optimized doping concentration of Eu3+ was 9 mol% for the highest emission intensity at 612 nm, and the concentration quenching occurred when the concentration of Eu3+ was beyond 9 mol%. The temperature-dependent luminescent properties of the phosphors showed that they had good thermal stability from room temperature to 498 K. This phosphor matched well with the output wavelength of commercial near-UV LED chips (∼394 nm) and blue LED chips (∼460 nm), and the work might provide some insights into the development of white light emission devices.
Co-reporter:Hao Xiong, Giovanni DeLuca, Yichuan Rui, Yaogang Li, Elsa Reichmanis, Qinghong Zhang, Hongzhi Wang
Solar Energy Materials and Solar Cells 2017 Volume 166(Volume 166) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.solmat.2017.03.028
•Develop a facile simple preparation method for perovskite films under the ambient condition.•The surface of the perovskite films exhibits compact uniform morphology.•The PSCs have good photovoltaic performance with compact perovskite as the active layer.The photovoltaic performance of perovskite solar cells is extremely dependent on the crystallization and morphology of the perovskite film, which are affected by the deposition method. Here, we demonstrate a simple approach to form a microporous PbI2 film, with subsequent conversion to a compact, highly crystalline perovskite film. The PbI2 and corresponding perovskite films were further probed by two-dimensional X-ray diffraction. The resultant perovskite exhibited improved photovoltaic performance under ambient conditions with about 50% humidity. The PbI2 microporous structure was formed by exchanging residual DMSO with DMF vapor in the PbI2 film, which facilitated contact with the methylammonium iodide (MAI) solution. The process resulted in the formation of compact, smooth, pinhole-free perovskite films having no residual PbI2. Solar cells fabricated using this methodology exhibited power conversion efficiencies over 16% with negligible photocurrent hysteresis.
Co-reporter:Wei Gong, Chengyi Hou, Yinben Guo, Jie Zhou, Jiuke Mu, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Nano Energy 2017 Volume 39(Volume 39) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.nanoen.2017.08.003
•A stretchable sheath-core structural triboelectric fiber (SSCTEF) is developed.•The SSCTEF exhibits high strain/stress sensitivity.•The self-powered sensing mechanism based on a built-in wavy is investigated.•The wearable sensor can detect and discriminate various kinds of motions.While the emerging stretchable electronic sensors have been demonstrated as promising wearable functional devices, challenges in achieving highly stretchable and self-powered fiber-like sensors still exist. Here, a stretchable sheath-core structural triboelectric fiber (SSCTEF) is developed to serve as a self-powered multifunctional kinematic sensor. Owing to the advanced built-in wavy structure design, the fiber-like sensor exhibits an ultrahigh working strain (100%) and demonstrates high sensitivity in response to not only stretching but also to bending and compressing. The working principle of the SSCTEF is verified by the coupling of numerical calculations and experimental measurements. A comprehensive study is carried out to investigate the factors that influence the output performance of the SSCTEF. By wearing, it is capable of detecting and discriminating the joint movements of human bodies. By further weaving and construction, it also shows potential for detecting the deformation in two-dimensional region. This work provides new opportunities for wearable and self-powered sensing fibers with full potential in human motion monitoring.A kinematic sensing fiber that is highly stretchable and self-powered is developed based on a triboelectric sheath-core structure. In which a unique built-in wavy is built in the core fiber and provides controllable electric contact to the intrinsically stretchable sheath fiber tube. The new design offers opportunities for stretchable and active sensing fibers with full potential in human motion monitoring.Download high-res image (152KB)Download full-size image
Co-reporter:Yanfang Yue, Haizeng Li, Kerui Li, Jinmin Wang, Hongzhi Wang, Qinghong Zhang, Yaogang Li, Pei Chen
Journal of Physics and Chemistry of Solids 2017 Volume 110(Volume 110) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jpcs.2017.06.022
•We introduced a complementary ECD based on WO3·0.33H2O/PEDOT and PB thin films for the first time.•The as-assembled complementary ECD exhibits superior electrochromic performance.•The excellent electrochromic performance of the complementary ECD will provide potential applications in energy-saving smart windows and displays.The device assembly plays an important role in affecting the electrochromic (EC) performance of an electrochromic device (ECD). Here, WO3·0.33H2O films are fabricated by a hydrothermal method and then PEDOT:PSS are spin-coated on the surface of WO3·0.33H2O films. Finally, the WO3·0.33H2O/PEDOT films are assembled with electrodeposited prussian blue (PB) to fabricate the WO3·0.33H2O/PEDOT-PB complementary electrochromic devices (ECDs). Compared with pure WO3·0.33H2O and WO3·0.33H2O/PEDOT single-active-layer structure ECDs, the complementary ECD exhibits higher optical modulation, higher coloration efficiency and faster response time, which would provide a promising platform for energy-saving smart (ESS) window.Download high-res image (195KB)Download full-size image
Co-reporter:Yaoqing Chu, Zhifu Liu, Qinghong Zhang, Hong Fang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2017 Volume 728(Volume 728) pp:
Publication Date(Web):25 December 2017
DOI:10.1016/j.jallcom.2017.08.281
•Eu3+-activated Yb2Si2O7 red phosphors were synthesized by a simple method.•The abnormal reduction phenomenon of Eu3+→ Eu2+ in YSO: Eu phosphor was reported.•The reduction mechanism from Eu3+ to Eu2+ in the compounds was discussed.Generally, the reduction of Eu3+ to Eu2+ in solids requires annealing in a reducing atmosphere. In this work, we find that the reduction of Eu3+ to Eu2+ can be realized in Yb2Si2O7 phosphors after being soaked in boiling water. Eu3+-activated Yb2Si2O7 with different doping concentrations was synthesized by a sol-gel method. The as-prepared Yb2Si2O7:Eu3+ phosphors showed strong red emission at 612 nm under ultraviolet light, corresponding to the 5D0 → 7F2 transition of Eu3+. The optimized doping concentration of Eu3+ was 7 mol% with the highest emission intensity at 612 nm. The valence change and luminescence properties of Eu-doped Yb2Si2O7 phosphors after being soaked in boiling water are reported and the reduction mechanism from Eu3+ to Eu2+ in the compounds is discussed. Our findings suggest that this kind of Eu3+ → Eu2+ valence transfer might shed light on the development of phosphors for display applications.Download high-res image (199KB)Download full-size image
Co-reporter:Zhenhua Chen, Qinghong Zhang, Yaogang Li, Hongzhi Wang, Rong-Jun Xie
Journal of Alloys and Compounds 2017 Volume 715(Volume 715) pp:
Publication Date(Web):25 August 2017
DOI:10.1016/j.jallcom.2017.04.270
•Phase purity adjustable LSN: Ce and MLSN: Ce phosphor were obtained.•Phase and PL properties can be adjusted by control of alkaline-earth metal ions.•Raw material ration of La/Si played a key role in LSN phase purity.•Warm-light white LEDs fabricated showed relatively low CCT and high CRI.The high correlated colour temperature (CCT) and deficient thermal stability of widely-used YAG:Ce and InGaN white light systems prompt an urgent need for more outstanding succedaneum phosphors, among which Ce-doped La3Si6N11 (LSN:Ce) phosphor has the best performance in the yellow-orange area. However, it still has not gained popularity due to its low quantum efficiency and luminance quality, caused by many factors such as irregular particle morphology and impure chemical composition, especially the difficulty of obtaining a single phase without LaSi3N5 impurity. By doping with different alkaline-earth metal elements and adjustment of the lanthanum/silicon ratio in the raw materials, LSN:Ce and MLSN:Ce (M = Ca, Ba and Sr) phosphors with high purity were synthesised in this work. Compared to Ca and Sr, doping with Ba produced a better result, not only in the crystallisation of the LSN phase, but also in the red shift of the phosphor emission. To further improve the purity of LSN phosphors, the Si/La molar ratio was increased from 2:1 to 1:1.5, and finally resulting in a single phase when the ratio reached 1:1. The white LEDs fabricated with the LSN:Ce & BaLSN:Ce phosphors and InGaN blue light chips had lower CCTs at 3900 K and 3300 K, indicating the great potential of the phosphor for application in high power and display lighting.
Co-reporter:Yufei Liu, Qiuwei Shi, Chengyi Hou, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Carbon 2017 Volume 125(Volume 125) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.carbon.2017.09.072
Many efforts have been devoted to fabricating three-dimensional graphene-derived aerogels owing to their promising real-world applications. However, it is still a challenge to fabricate a pure graphene-based aerogels with both high mechanical strength and conductivity. In this study, we report a facile and scalable method to prepare pure chemically converted graphene aerogels (CCGA) from high-concentration gel precursors with the assistance of two-step freeze-drying. The CCGA demonstrates a high compressive strength of 106.1 kPa under a strain of 80%. Its resistance in the thickness direction is variable and reaches as low as 6.6 Ω at a compressive strain of 90%. The aerogels also show many interesting behaviors and properties, including promising Joule heating-assisted oil absorption, non-flammability, and the ability to sense a wide range of applied pressure.Download high-res image (418KB)Download full-size image
Co-reporter:Minwei Zhang;Chengyi Hou;Arnab Halder;Qijin Chi
Materials Chemistry Frontiers 2017 vol. 1(Issue 1) pp:37-60
Publication Date(Web):2016/11/30
DOI:10.1039/C6QM00145A
Paper is an attractively assembled form of materials and has accompanied our daily life almost everywhere. Two-dimensional layered materials, especially graphene, have unique intrinsic structures to be exploited for smart architecture of macroscopic papers that are offering many newly emerging applications. Research advances in graphene based papers in the past few years have created a new category of composite materials. This review aims at offering an up-to-date comprehensive summary of graphene-supported papers, with the emphasis on smart assembly and purpose-driven specific functionalization for their critical applications associated with sensing, environmental and energy technologies. The contents of this review are based on a balance combination of our own studies and selected research studies done by worldwide academic groups. We first give a brief introduction to graphene as a versatile building block and to the current status of research studies on graphene papers. This is followed by addressing some crucial methods of how to prepare graphene papers. We then summarize multiple possibilities of functionalizing graphene papers, membranes or films. Finally, we evaluate some key applications of graphene papers in the areas of chemical/electrochemical sensors, biomimetics and energy storage devices, just before leading to our concluding remarks and perspectives.
Co-reporter:Hongwei Fan;Kerui Li;Qiang Li;Chengyi Hou;Qinghong Zhang;Yaogang Li;Wusong Jin
Journal of Materials Chemistry C 2017 vol. 5(Issue 37) pp:9778-9785
Publication Date(Web):2017/09/28
DOI:10.1039/C7TC03358C
Silver nanowire/poly(dimethylsiloxane) (AgNW/PDMS)-based stretchable conductive films are widely studied due to their excellent comprehensive performances mainly derived from the great electrical conductivity of AgNWs together with the excellent mechanical and optical properties of PDMS. However, their further applications have been limited by two fatal shortcomings: the low surface energy of PDMS and poor elongation at break of AgNWs. Herein, an ultrathin PDMS-immobilized layer was prepared to construct a semi-embedded wrinkled AgNW network and overcome the limitations through spin-coating the pre-polymerized PDMS solution. As a result, the as-prepared transparent stretchable AgNW/PDMS composite films with different AgNW loadings demonstrate great transmittance, conductivity, tensile stability under 40% and 60% strains, and adhesion of AgNWs on the PDMS substrate. With a further increase of AgNW loadings, reflective stretchable conductive films were obtained and they showed a much lower sheet resistance (∼0.2 Ω sq−1) and good tensile stability under 70% strain. Based on these stretchable conductive films, stretchable electrothermal chromatic films and electrothermal actuators were fabricated to demonstrate their multifunctional applications.
Co-reporter:Yinben Guo;Yaogang Li;Qinghong Zhang
Journal of Materials Chemistry C 2017 vol. 5(Issue 6) pp:1436-1442
Publication Date(Web):2017/02/09
DOI:10.1039/C6TC04771H
Inspired by the human eye, an electronic eye (e-eye) is a photodetector that senses optical signals. To solve the problems of power supply and the limitation of application only in the visible region, a self-powered, multifunctional e-eye for UV and IR light detection was developed. The e-eye harvests mechanical and thermal energy from the ambient environment by the triboelectric and thermoelectric effect to power itself. ZnO and RGO were chosen as active UV and IR photosensitive materials, respectively, and were vertically integrated into a single device with a multilayer structure. The self-powered, e-eye has good photoelectric properties. Moreover, it can distinguish UV and IR irradiation of different intensities individually or simultaneously through the generation of different electric signals, endowing the e-eye great with potential applications in portable/wearable UV and IR detection devices.
Co-reporter:Qiuwei Shi;Jiahui Li;Chengyi Hou;Yuanlong Shao;Qinghong Zhang;Yaogang Li
Chemical Communications 2017 vol. 53(Issue 81) pp:11118-11121
Publication Date(Web):2017/10/10
DOI:10.1039/C7CC03408C
A novel near-infrared (NIR) light-responsive sodium polyacrylate (PAAS)/graphene oxide (GO) fiber with a torsional pre-deformation structure is reported to realize remote control actuation. The torsional pre-deformed PAAS/GO fiber exhibited various actuation phenomena, under the control of a low powered near-infrared light (50 mW cm−2), such as rotating in a low-temperature range (<25 °C), rolling a distance of 10 times of its diameter within 10 s, and even driving the shape change of a fabric (the weight is as high as 20 times of the fiber itself).
Co-reporter:Qiuwei Shi;Jiahui Li;Chengyi Hou;Yuanlong Shao;Qinghong Zhang;Yaogang Li
Chemical Communications 2017 vol. 53(Issue 81) pp:11118-11121
Publication Date(Web):2017/10/10
DOI:10.1039/C7CC03408C
A novel near-infrared (NIR) light-responsive sodium polyacrylate (PAAS)/graphene oxide (GO) fiber with a torsional pre-deformation structure is reported to realize remote control actuation. The torsional pre-deformed PAAS/GO fiber exhibited various actuation phenomena, under the control of a low powered near-infrared light (50 mW cm−2), such as rotating in a low-temperature range (<25 °C), rolling a distance of 10 times of its diameter within 10 s, and even driving the shape change of a fabric (the weight is as high as 20 times of the fiber itself).
Co-reporter:Qiang Li;Kerui Li;Hongwei Fan;Chengyi Hou;Yaogang Li;Qinghong Zhang
Journal of Materials Chemistry C 2017 vol. 5(Issue 44) pp:11448-11453
Publication Date(Web):2017/11/16
DOI:10.1039/C7TC02471A
A stretchable and multicolor electrothermal chromatic fiber is prepared based on reduced graphene oxide (RGO) functionalized elastic conductive fibers and various thermochromic materials. The colors of the fibers can be switched within 15s due to the good resistive-heating performance of the conductive fibers. Through a combination of different thermochromic materials, abundant and reversible color changes are clearly observed by the naked eye (e.g., from orange, red, green to yellow, purple, blue and white, respectively). Moreover, the fibers exhibit excellent color changing stability even after 1000 resistive-heating or stretching/releasing cycles owing to the structural stability of the multilayered fibers and the excellent electrothermal stability of RGO. Finally, they are easily woven into textiles and plaited into colorful hand chains, which showed huge application value especially for stretchable visual sensors and clothing integrated wearable displays.
Co-reporter:Wei Zhang;Chengyi Hou;Yaogang Li;Qinghong Zhang
Nanoscale (2009-Present) 2017 vol. 9(Issue 45) pp:17821-17828
Publication Date(Web):2017/11/23
DOI:10.1039/C7NR05575G
Flexible and multifunctional sensors that continuously detect physical information are urgently required to fabricate wearable materials for health monitoring. This study describes the fabrication and performance of a strong and flexible vessel-like sensor. This electronic vessel consists of a self-supported braided cotton hose substrate, single-walled carbon nanotubes (SWCNTs)/ZnO@polyvinylidene fluoride (PVDF) function arrays and a flexible PVDF function fibrous membrane, and it possesses high mechanical property and accurate physical sensing. The rationally designed tubular structure facilities the detection of the applied temperature and strain and the frequency, pressure, and temperature of pulsed fluids. Therefore, the flexible electronic vessel holds promising potential for applications in wearable or implantable materials for the monitoring of health.
Co-reporter:Junxing Meng;Jiuke Mu;Chengyi Hou;Qinghong Zhang;Yaogang Li
Nanoscale (2009-Present) 2017 vol. 9(Issue 35) pp:12963-12968
Publication Date(Web):2017/09/14
DOI:10.1039/C7NR03028B
Flexible actuators are widely in demand for many real-life applications. Considering that existing actuators based on polymers, low-dimensional materials and pore-rich materials are mostly limited by slow response rate, high driving voltage and poor stability, we report here a novel metal based flexible actuator which is fabricated simply through partial oxidation and nano-function of copper foil with the assistance of reduced graphene oxide. The obtained asymmetric metallic actuator is (electric-)thermally driven and exhibits fast response rate (∼2 s) and large curvature (2.4 cm−1) under a low voltage (∼1 V) with a sustainable operation of up to ∼50 000 cycles. The actuator can also be triggered by infrared irradiation and direct-heating under various conditions including air, water, and vacuum.
Co-reporter:Jiahui Li, Yuanlong Shao, Qiuwei Shi, Chengyi Hou, Qinghong Zhang, Yaogang Li, Richard B. Kaner, Hongzhi Wang
Nano Energy 2017 Volume 38(Volume 38) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.nanoen.2017.06.013
•Developing a continuous and stable way to transfer GO ink and write large-area rGO film by Chinese brush.•Large-area folded and wavy rGO film were fabricated with a controllable writing process.•All-solid-state single/foldable supercapacitors have been directly written by Chinese brush.•Three series/parallel connection of foldable supercapacitors were obtained and shows 2.4 V output voltage and 258.6 mF cm−2 areal capacitance.Chinese brush, made of a bundle of animal hairs in a quasi-parallel arrangement, is an effective tool that can be used to continuously place low-viscosity ink onto different substrates with high ink mass loading. Here, we demonstrate a highly effective approach to coat graphene onto rough and even crumpled substrates by using a Chinese brush. By combining forces including Laplace pressure differential, asymmetric retention and gravity, the low-viscosity graphene oxide ink can be sufficiently transferred onto different substrates through the brush hairs in a controlled manner. The as-prepared graphene films are used as electrodes for all-solid-state foldable supercapacitors. Using series and/or parallel connections, the energy storage performance of the foldable all-solid-state supercapacitors can be tailored to provide different output voltages and currents. The voltage of the three series connected devices with gel electrolyte can be extended to 2.4 V. A parallel connected foldable all-solid-state supercapacitor exhibits promising electrochemical performance, such as high areal capacitance of 258.6 mF cm−2, good energy density of 23.1 μW h cm−2 and power density of 0.2 mW cm−2. This work offers an alternative method of GO ink transfer, graphene film production and the fabrication of flexible electronics.We demonstrate a highly effective approach to coating graphene films onto rough or even crumpled substrates by using a Chinese brush. The produced graphene films are used as electrodes for all-solid-state foldable supercapacitors. By making series or parallel connections, the energy storage performance of the all-solid-state foldable supercapacitors can be adjusted to different output voltages and currents.Download high-res image (151KB)Download full-size image
Co-reporter:Chengyi Hou;Minwei Zhang;Takeshi Kasama;Christian Engelbrekt;Lili Zhang;Qijin Chi
Advanced Materials 2016 Volume 28( Issue 21) pp:4097-4104
Publication Date(Web):
DOI:10.1002/adma.201505990
Co-reporter:Yuanlong Shao;Maher F. El-Kady;Cheng-Wei Lin;Guanzhou Zhu;Kristofer L. Marsh;Jee Youn Hwang;Qinghong Zhang;Yaogang Li;Richard B. Kaner
Advanced Materials 2016 Volume 28( Issue 31) pp:6719-6726
Publication Date(Web):
DOI:10.1002/adma.201506157
Co-reporter:Kerui Li, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2016 vol. 4(Issue 24) pp:5849-5857
Publication Date(Web):23 May 2016
DOI:10.1039/C6TC01516F
Mechanical and electrochemical stability issues of electrode materials have been long-standing obstacles restricting the development of highly flexible electrochromics. Herein, a lightweight, highly bendable and foldable electrochromic (EC) film is realized through the construction of mechanically and electrochemically stable bilayer nanowire networks (BNNs) on ultra-thin polyethylene terephthalate (PET) substrates. These BNNs composed of silver nanowires (AgNWs) and W18O49 nanowires (W18O49NWs) are prepared using a facile and continuous spray-coating method. An alginic acid/poly(dopamine) complex (Aa–PDA) and a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer are used as a binder and a charge balancing layer, respectively, to enhance the interfacial and structural stability of nanowires and prevent the electrochemical corrosion of AgNWs. These optimized and highly flexible EC films exhibit good optical contrast, high coloration efficiency (up to 118.1 cm2 C−1), highly enhanced electrochemical stability and excellent structural stability even after 500 bending or 100 folding cycles. Moreover, EC films per square centimeter weigh less than 2.3 mg. The spray-coating method is easily controlled and allowed for convenient patterning, which is important for real-life applications.
Co-reporter:Haizeng Li, Jingwei Chen, Mengqi Cui, Guofa Cai, Alice Lee-Sie Eh, Pooi See Lee, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2016 vol. 4(Issue 1) pp:33-38
Publication Date(Web):16 Nov 2015
DOI:10.1039/C5TC02802G
Ultrathin tungsten molybdenum oxide nanoparticle films were fabricated from aqueous ink by a spray coating technique. With the in situ heating of the hot plate during the spray coating process, the detrimental effects of oxygen vacancies on electrochromic (EC) materials could be eliminated. The spray coated ultrathin films exhibit higher contrast than the drop casted films, which would provide a versatile and promising platform for energy-saving smart (ESS) windows, batteries, and other applications.
Co-reporter:Hao Xiong, Yichuan Rui, Yaogang Li, Qinghong Zhang and Hongzhi Wang
Journal of Materials Chemistry A 2016 vol. 4(Issue 28) pp:6848-6854
Publication Date(Web):27 Jun 2016
DOI:10.1039/C6TC02238C
Lead halide perovskite solar cells with high efficiency have recently attracted tremendous attention. However, the poor stability of perovskite materials has hindered their practical applications. Here, we presented a hydrophobic agent, fluoroalkyl silane, to modify both the light absorbing layer and the hole transport layer. In the presence of a hydrophobic coating, we obtained a stable perovskite solar cell with less hysteresis between the forward sweep and the reverse sweep in air. The effect of fluoroalkyl silane concentration on the stability was investigated; with an optimized 2.0 wt% fluoroalkyl silane solution treatment, the efficiency of perovskite solar cells has reached over 12.0 ± 0.4%. Moreover, for those perovskite solar cells that are exposed to air with about 50% relative humidity, the efficiency was maintained at around 12% for a duration of more than 500 h, while the efficiency of those without hydrophobic coating sharply decreased from about 12% to 1% in a duration of 250 h.
Co-reporter:Yinben Guo, Kerui Li, Chengyi Hou, Yaogang Li, Qinghong Zhang, and Hongzhi Wang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 7) pp:4676
Publication Date(Web):January 26, 2016
DOI:10.1021/acsami.5b11622
The rapid development of wearable electronics in recent years has brought increasing energy consumption, making it an urgent need to focus on personal energy harvesting, storage and management. Herein, a textile-based personal energy management device with multilayer-coating structure was fabricated by encapsulating commercial nylon cloth coated with silver nanowires into polydimethylsiloxane using continuous and facile dip-coating method. This multilayer-coating structure can not only harvest mechanical energy from human body motion to power wearable electronics but also save energy by keeping people warm without losing heat to surroundings and wasting energy to heat empty space and inanimate objects. Fluoroalkylsilanes (FAS) were grafted onto the surface of the film through one single dip-coating process to improve its energy harvesting performance, which has hardly adverse effect to heat insulation and Joule heating property. In the presence of FAS modification, the prepared film harvested mechanical energy to reach a maximum output power density of 2.8 W/m2, charged commercial capacitors and lighted LEDs, showing its potential in powering wearable electronics. Furthermore, the film provided 8% more thermal insulation than normal cloth at 37 °C and efficiently heated to 40 °C within 4 min when applied the voltage of only 1.5 V due to Joule heating effect. The high flexibility and stability of the film ensures its wide and promising application in the wearable field.Keywords: FAS; heat insulation; personal energy management; triboelectric nanogenetator; wearable heater
Co-reporter:Gang Wang, Kerui Li, Francis J. Purcell, De Zhao, Wei Zhang, Zhongyuan He, Shuai Tan, Zhenguan Tang, Hongzhi Wang, and Elsa Reichmanis
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 37) pp:24974
Publication Date(Web):September 1, 2016
DOI:10.1021/acsami.6b10542
A materials fabrication concept based on a fluid-construction strategy to create three-dimensional (3D) ZnO@ZnS-Ag active nanostructures at arbitrary position within confined microchannels to form an integrated microfluidic surface-enhanced Raman spectroscopy (SERS) system is presented. The fluid-construction process allowed facile construction of the nanostructured substrates, which were shown to possess a substantial number of integrated hot spots that support SERS activity. Finite-difference time-domain (FDTD) analysis suggested that the 3D clustered geometry facilitated hot spot formation. High sensitivity and good recycle performance were demonstrated using 4-mercaptobenzoic acid (4-MBA) and a mixture of Rhodamine 6G (R6G) and 4-MBA as target organic pollutants to evaluate the SERS microfluidic device performance. The 3D clustered nanostructures were also effective in the detection of a representative nerve agent and biomolecule. The results of this investigation provide a materials and process approach to the fabrication of requisite nanostructures for the online detection of organic pollutants, devices for real-time observation of environmental hazards, and personal-health monitoring.Keywords: biomolecule detection; clustered nanostructures; fluid construction; microfluidic technology; SERS detection
Co-reporter:Gang Wang, Ping-Hsun Chu, Boyi Fu, Zhongyuan He, Nabil Kleinhenz, Zhibo Yuan, Yimin Mao, Hongzhi Wang, and Elsa Reichmanis
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 37) pp:24761
Publication Date(Web):August 26, 2016
DOI:10.1021/acsami.6b07548
Solution shearing has attracted great interest for the fabrication of robust and reliable, high performance organic electronic devices, owing to applicability of the method to large area and continuous fabrication, as well as its propensity to enhance semiconductor charge transport characteristics. To date, effects of the design of the blade shear features (especially the microfluidic shear design) and the prospect of synergistically combining the shear approach with an alternate process strategy have not been investigated. Here, a generic thin film fabrication concept that enhanced conjugated polymer intermolecular alignment and aggregation, improved orientation (both nanoscale and long-range), and narrowed the π–π stacking distance is demonstrated for the first time. The impact of the design of shearing blade microfluidic channels and synergistic effects of fluid shearing design with concomitant irradiation strategies were demonstrated, enabling fabrication of polymer-based devices with requisite morphologies for a range of applications.Keywords: alignment; charge transport; conjugated polymers; microfluidic shear
Co-reporter:Qiuwei Shi, Chengyi Hou, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Chemical Communications 2016 vol. 52(Issue 34) pp:5816-5819
Publication Date(Web):16 Mar 2016
DOI:10.1039/C6CC01590E
A novel all-solid electrically controllable Au@graphene oxide (GO) actuator with a bilayer structure is reported to address many of the limitations of traditional electrical-driven materials including complicated layouts and high electric fields. Specifically, the obtained Au@GO actuator possesses electrolyte-free, real time controlled actuation and patterning capabilities.
Co-reporter:Yuanqiang Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Power Sources 2016 Volume 318() pp:128-135
Publication Date(Web):30 June 2016
DOI:10.1016/j.jpowsour.2016.04.012
•Develop a facile preparation method for CuxS coated on FTO glass counter electrode.•The surface of the CuxS films exhibit uniform nanosheet morphology.•The CuxS films have good adhesion with FTO glass substrate.•The QDSSCs have good photovoltaic performance with CuxS/FTO as counter electrode.The nanosheet-structured CuxS thin films used as counter electrodes (CEs) for CdS/CdSe quantum dot sensitized solar cells (QDSSCs) have been in situ prepared via the sulfidation of Cu nanoparticles deposited on F-doped SnO2 glass (FTO glass) substrate by magnetron sputtering method. The thickness of the deposited Cu film affects the morphology and thickness of the obtained CuxS films. The CuxS nanosheet films have good adhesion with FTO glass and the surface exhibits uniform morphology. The characteristics of QDSSCs are studied in more detail by photocurrent-voltage performance measurements, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy (EIS). The CuxS on FTO glass (CuxS/FTO) CEs show much higher power conversion efficiency (PCE) and IPCE than those of the Pt on FTO (Pt/FTO) CE because of their superior carrier mobility and electro-catalytic ability for the polysulfide redox reactions. Based on an optimal CuxS film thickness of 2.7 μm obtained by the sulfidation of the Cu film thickness of 300 nm on FTO, the best photovoltaic performance with PCE of 3.67% (Jsc = 16.47 mA cm−2, Voc = 0.481 V, FF = 0.46) under full one-sun illumination is achieved.
Co-reporter:Yang Guo, Jiuke Mu, Chengyi Hou, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Carbon 2016 Volume 107() pp:146-153
Publication Date(Web):October 2016
DOI:10.1016/j.carbon.2016.05.063
Thermoelectric (TE) generators, being able to convert temperature gradients into electricity, are an appealing eco-friendly energy harvesting technology. In order to broaden the applications of TE materials, many researchers have focused their efforts towards flexible TE materials to substitute the commercial rigid TE devices. Most of these works used polymers as flexible TE materials, but their lower efficiency and melting point in comparison to inorganic TE materials are limiting factors for many applications. Here, we report the fabrication of a flexible and thermostable TE generator based on porous all-graphene films. The output power of the generator is up to 0.43 μW for a temperature gradient of 75 K. In addition, it runs at 550 K higher temperature than current flexible TE devices, which allows its application at much higher temperatures than conventional flexible TE.
Co-reporter:Jie Zhang, Yichuan Rui, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2016 Volume 204() pp:227-234
Publication Date(Web):20 June 2016
DOI:10.1016/j.electacta.2016.04.057
•TiO2 submicrospheres (200 nm) with a high surface area were prepared by the hydrothermal method from Ti(SO4)2 and (NH4)2SO4 solution.•By using TiO2 submicrosphere scattering particles on top of semitransparent layer, the power conversion efficiency of DSSCs improved to 9.07%.•Relationship between the efficiency with EIS interfacial resistance of DSSC under 0.1 to 1.0 sun irradiation was analyzed.Hierarchical anatase TiO2 submicrospheres were synthesized by direct hydrothermal method at 120 °C using Ti(SO4)2 and (NH4)2SO4 mixed solution as precursor. The calcined spheres in particle size of 150–200 nm, which consisted of closely connected nanocrystals in a crystallite size of about 24.2 nm and had a relatively high specific surface area of 43.2 m2 g−1 compared to microspheres. In presence of TiO2 submicrospheres as the scattering layer on top of semitransparent layer, the power conversion efficiency of dye-sensitized solar cells (DSSCs) was increased to as high as of 9.07% from 7.24%. This remarkable improvement compared to commercial scattering particles (efficiency of 8.33%) is mainly attributed to their higher surface area for increasing the loading of dye molecule as well as a lower resistance under 1 sun irradiation. The relationship between the conversion efficiency of DSSCs with interfacial resistance under 0.1 to 1.0 sun illumination was further investigated, the decrease of the light power density led to the increase of interfacial resistance. Moreover, even under 0.1 sun irradiation, DSSC still had an efficiency of 7.18% but a slightly lower Voc of 0.597 V.Anatase TiO2 submicrospheres with high surface area were prepared and used for the scattering layer of DSSCs, leading to an efficiency from 7.24% to 9.07%.
Co-reporter:Dongchen Che, Xiaoxu Zhu, Hongzhi Wang, Yourong Duan, Qinghong Zhang, Yaogang Li
Journal of Colloid and Interface Science 2016 Volume 463() pp:1-7
Publication Date(Web):1 February 2016
DOI:10.1016/j.jcis.2015.10.039
Efficient synthetic methods for near-infrared quantum dots with good biophysical properties as bioimaging agents are urgently required. In this work, a simple and fast synthesis of highly luminescent, near-infrared AgInSe2–ZnSe quantum dots (QDs) with tunable emissions in aqueous media is reported. This method avoids high temperature and pressure and organic solvents to directly generate water-dispersible AgInSe2–ZnSe QDs. The photoluminescence emission peak of the AgInSe2–ZnSe QDs ranged from 625 to 940 nm, with quantum yields up to 31%. The AgInSe2–ZnSe QDs with high quantum yield, near-infrared and low cytotoxic could be used as good cell labels, showing great potential applications in bio-imaging.
Co-reporter:Shenglong Shang, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Journal of Colloid and Interface Science 2016 Volume 483() pp:11-16
Publication Date(Web):1 December 2016
DOI:10.1016/j.jcis.2016.08.005
A new type of photonic crystal PDMS fiber which exhibits tunable structural color upon exposure to external magnetic field is described in this article. The novel magnetic field responsive fiber was prepared from embedding ethylene glycol droplets (containing Fe3O4@C nanoparticles) into PDMS. In the presence of an external magnetic field, Fe3O4@C nanoparticles which dispersed in ethylene glycol droplets formed one dimensional chain-like structures along the magnetic field. As a result, the color of the fiber changes to yellow green. By contrast, when the magnetic field was removed, the color of the fiber will disappear and display its original color. Moreover, this novel PDMS fiber has good mechanical properties and could keep its color under a fixed magnetic field no matter it was stretched or squeezed. This study is expected to have some important applications such as none-powered and functionalized fibers for camouflage.A new type of photonic crystal PDMS fiber exhibits tunable structural color upon exposure to external magnetic field.
Co-reporter:De Zhao, Zhongyuan He, Gang Wang, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Journal of Colloid and Interface Science 2016 Volume 478() pp:227-235
Publication Date(Web):15 September 2016
DOI:10.1016/j.jcis.2016.05.054
•Inverse opal titanium dioxide-zirconium dioxide film was firstly fabricated.•Inverse opal composite films were firstly introduced into microfluidic device.•The films-based microfluidic device enriches mono-/multi-phosphopeptides efficiently.HypothesisMicrofluidic technology plays a significant role in separating biomolecules, because of its miniaturization, integration, and automation. Introducing micro/nanostructured functional materials can improve the properties of microfluidic devices, and extend their application. Inverse opal has a three-dimensional ordered net-like structure. It possesses a large surface area and exhibits good mass transport, making it a good candidate for bio-separation. This study exploits inverse opal titanium dioxide-zirconium dioxide films for on-chip phosphopeptide enrichment.ExperimentsTitanium dioxide-zirconium dioxide inverse opal film-based microfluidic devices were constructed from templates of 270-, 340-, and 370-nm-diameter poly(methylmethacrylate) spheres. The phosphopeptide enrichments of these devices were determined by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.FindingsThe device constructed from the 270-nm-diameter sphere template exhibited good comprehensive phosphopeptide enrichment, and was the best among these three devices. Because the size of opal template used in construction was the smallest, the inverse opal film therefore had the smallest pore sizes and the largest surface area. Enrichment by this device was also better than those of similar devices based on nanoparticle films and single component films. The titanium dioxide-zirconium dioxide inverse opal film-based device provides a promising approach for the efficient separation of various biomolecules.
Co-reporter:Dongyu Xu, Yichuan Rui, Vernon Tebong Mbah, Yaogang Li, Qinghong Zhang, Hongzhi Wang
International Journal of Hydrogen Energy 2016 Volume 41(Issue 2) pp:873-881
Publication Date(Web):12 January 2016
DOI:10.1016/j.ijhydene.2015.10.113
•An earth-abundant Ti-doped α-Fe2O3/NiFeOx photoanode was fabricated by spin-coating.•The highest photocurrent 1.13 mA/cm2 at 1.23 V with 55 mV cathode shift was achieved.•EIS indicated the enhanced charge transfer rate comes from improvement of water oxidation.In this article, a novel and facile strategy to load low-cost and earth-abundant oxygen evolution catalyst NiFeOx by spin-coating on Ti-doped α-Fe2O3 films was reported. The NiFeOx modified hematite photoanode was prepared by a two-step process, which consisted of a hydrothermal method and a subsequent NiFeOx loading step. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) were used to characterize the resulting photoanode. The highest photocurrent increment and lowest onset potential were observed with 30 mM NiFe precursor treatment. Increasing the loading content in a range from 10 to 90 mM, the photocurrent density increases from 0.998 for the pristine α-Fe2O3 to 1.126 mA/cm2 at 1.23 V vs RHE (i.e., 12.7% increment) with 30 mM NiFe precursor treatment. Concomitant with this improvement was a cathode shift in the onset potential by nearly 55 mV and higher incident-photon-to-current efficiencies. Hematite photoanodes after NiFeOx deposition showed better performance than pristine samples, because of a lower overpotential for water oxidation resulted from NiFeOx modifying.The α-Fe2O3/NiFeOx composite photoanode was prepared by spin-coating, which achieved photocurrent density as high as 1.126 mA/cm2 at 1.23 V vs RHE.
Co-reporter:Dongchen Che, Di Ding, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Journal of Alloys and Compounds 2016 Volume 678() pp:51-56
Publication Date(Web):5 September 2016
DOI:10.1016/j.jallcom.2016.03.172
•Ag2SeZnSe nanocrystals are prepared directly in aqueous media at low temperature.•Ag2SeZnSe nanocrystals show excellent water solubility and colloidal stability.•Ag2Se nanocrystals exhibit tunable near-infrared emission with ultrasmall size.•Ag2SeZnSe nanocrystals show high quantum yield with low cytotoxicity.•Ag2SeZnSe nanocrystals are stable over a month at room temperature in the air.Efficient aqueous synthetic methods for near-infrared quantum dots as bioimaging agents are urgently required. In this work, a simple and fast synthesis of highly luminescent, near-infrared Ag2Se quantum dots (QDs) in aqueous media is reported. The method avoids high temperature, pressure and organic solvents to directly generate water-dispersible Ag2Se QDs. The photoluminescence emission of Ag2Se QDs ranges from 835 to 940 nm by different Ag:Se molar ratio. Using the ZnSe as a shell, the quantum yield reaches up to 42%. The Ag2SeZnSe QDs with high quantum yield, near-infrared and low cytotoxic could be used as good cell labels, showing great potential applications in bio-imaging.
Co-reporter:De Zhao, Zhongyuan He, Gang Wang, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Sensors and Actuators B: Chemical 2016 Volume 229() pp:281-287
Publication Date(Web):28 June 2016
DOI:10.1016/j.snb.2016.01.125
•A novel ZnO/Zn(OH)F nanofiber arrays with high aspect ratio and vertical height of about 40 μm was constructed by a simple shortcut mean-microfluidic chemical method, which is much beneficial for the performance improvement of microfluidic system.•ZnO/Zn(OH)F nanofiber arrays-based microfluidic system exhibits excellent photocatalytic performance owing to high content and large contact area of zinc oxide.•ZnO/Zn(OH)F nanofiber arrays-based microfluidic system exhibits superior separation performance toward histidine-rich protein owing to the zinc- histidine coordination and high filling degree.Owing to the unique property of miniaturization and integration, microfluidic technology has been merged with many disciplines and exhibits its unique advantages in the corresponding areas. The property and performance of microfluidic system are tightly related to the property of inner surface of microchannel. As an important inorganic nanomaterial, zinc oxide is often applied to the modification of inner surface of microchannel as nanorods with low aspect ratio. However, zinc oxide nanorod only could provide limited contact area, which limits the application and performance of microfluidic system. So how to construct an efficient micro/nanostructured arrays with higher content and more contact area of zinc oxide in limited microspace via a simple method become an urgent issue to be addressed in the field of microfluidics. In this work, through microfluidic chemical method with the introduction of fluorine, a novel ZnO/Zn(OH)F nanofiber arrays was successfully constructed on inner surface of confined capillary microchannels (CMs). In the photocatalytic application, the nanofiber array-based CMs could almost photodegrade methylene blue solution (5 mg L−1) as the residence time was 40 s; based on the unique advantage of micro/nanostructure, in the application of bio-separation, the nanofiber array-based CMs could also absorb all the bovine hemoglobin (0.5 mg mL−1) as the residence time was 50 s and isolate human hemoglobin from human blood (500-fold diluted) effectively due to zinc-histidine coordination and large contact area. So it has been demonstrated that the ZnO/Zn(OH)F nanofiber array-based CMs would be an ideal microfluidic system for versatile applications, such as photocatalysis and proteomics.
Co-reporter:Haizeng Li, Jinmin Wang, Qiuwei Shi, Minwei Zhang, Chengyi Hou, Guoying Shi, Hongzhi Wang, Qinghong Zhang, Yaogang Li, Qijin Chi
Applied Surface Science 2016 380() pp: 281-287
Publication Date(Web):1 September 2016
DOI:10.1016/j.apsusc.2016.01.009
•Self-assemble 2D WO3·2H2O nanosheets were prepared by a facile and novel solution route.•Electrodeposition technique was selected to prepare electrochromic electrode for its attractive applications in constructing 3D quasi-vertical nanosheet electrodes.•3D WO3·2H2O nanosheet electrode shows superior electrochromic performance.•The excellent electrochromic performance of the electrodeposited WO3·2H2O electrode makes our electrochromic device very attractive for potential applications in energy-saving smart windows.Three-dimensional (3D) quasi-vertical nanosheet (QVNS) architectures are of great importance in the application of electrochromic devices due to its 3D porous structures, large surface area and lamellar permeable space of nanosheets. In this study, we demonstrate successful preparing of WO3·2H2O nanosheets via a novel and facile solution route and repurposing the typical electrodeposition technique to obtain 3D QVNS electrodes. The electrode was successfully assembled into an electrochromic device which exhibits good electrochromic performance.
Co-reporter:Jiahui Li, Yuanlong Shao, Xuecheng Chen, Hongzhi Wang, Yaogang Li, Qinghong Zhang
Progress in Natural Science: Materials International 2016 Volume 26(Issue 5) pp:503-509
Publication Date(Web):October 2016
DOI:10.1016/j.pnsc.2016.09.003
All-inorganic quantum dot light emitting diodes (QLEDs) have gained great attention as a result of their high stability under oxygen-rich, humid and high current working conditions. In this work, we have fabricated an all-inorganic QLED device (FTO/NiO/QDs/AZO/Ag) with sandwich-structure, wherein the inorganic metal oxides thin films of NiO and AZO were employed as hole and electron transport layers, respectively. The porous NiO layer with vertical lamellar nanosheets interconnected microstructure have been directly synthesized on the substrate of conductive FTO glass and increased the wettability of CdSe@ZnS QDs, which result in an enhancement of current transport performance of the QLED.
Co-reporter:Yuanlong Shao, Maher F. El-Kady, Lisa J. Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang, Mir F. Mousavi and Richard B. Kaner
Chemical Society Reviews 2015 vol. 44(Issue 11) pp:3639-3665
Publication Date(Web):22 Apr 2015
DOI:10.1039/C4CS00316K
The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors.
Co-reporter:Shenglong Shang, Zhifu Liu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 20) pp:11093-11097
Publication Date(Web):17 Apr 2015
DOI:10.1039/C5TA00775E
An elastic, structurally colored fiber with reversible structural color is described in this article. Using an external magnetic field, Fe3O4@C superparamagnetic colloidal nanocrystal clusters (SCNCs) formed one-dimensional chain-like photonic crystal structures and were embedded in a polyacrylamide matrix. When the fiber was stretched/squeezed in the horizontal direction, the size of the fiber reduced/increased in the vertical direction. As a result, the distance between each sphere in chain-like structures can be reversibly changed through the elastic deformation of the matrix, and the structurally colored fiber displays brilliant colors, ranging from red to green as the mechanical strain changes, which can be clearly observed by the naked eye. The reflection peak can be tuned from 637 nm to 515 nm as a function of fiber extrusion or elongation. The novel structurally colored fiber is expected to have some important applications such as the substitution of some fiber-based wearable electronic strain sensors because this fiber does not require any additional devices to provide energy.
Co-reporter:Qiuwei Shi, Chengyi Hou, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 18) pp:9882-9889
Publication Date(Web):27 Mar 2015
DOI:10.1039/C5TA00920K
Graphene foam with three-dimensional (3D) networks was formed following removal of the undesirable toxic iodide induced in a HI reduced GO film through NIR light irradiation via a near infrared (NIR) light irradiation method under ambient laboratory conditions. Compact reduced graphene oxide films were used as the precursors which were fabricated through vacuum filtration and HI reduction. A series of graphene foams which have alterable pore sizes ranging from a few to hundred micrometers rapidly formed under NIR light irradiation at different power densities. The graphene foam has an ultimate tensile strength of about 15.3 MPa and could be compressed at a very large strain (ε = 60%) for 200 cycles without significant plastic deformation or degradation in compressive strength. This 3D graphene network is hydrophobic and showed high absorbing abilities for organic liquids. The adsorbed oil weight is up to about 27 times the weight of graphene foam after being immersed in an oil–water mixture for two minutes, and 87.2% of adsorbed oil could be squeezed out and recycled. This process is highly repeatable, which makes our product a potential candidate for removal and recycling of oil for environmental protection.
Co-reporter:De Zhao, Gang Wang, Zhongyuan He, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 20) pp:4272-4281
Publication Date(Web):22 Apr 2015
DOI:10.1039/C5TB00324E
Three kinds of micro/nanostructured NiO arrays were constructed in confined microchannels via a facile and template-free microfluidic chemical fabrication method. Bovine serum albumin (BSA) and bovine hemoglobin (BHb) with different isoelectric points (IEPs) were chosen as the model proteins to test the absorption ability of NiO-modified microchannels for abundant proteins via electrostatic interaction and affinity interaction. The influences of the pH and ionic strength of the protein solution, the residence time of protein solution in the microchannels, zeta potentials and morphologies of nickel oxide on the protein absorption behavior of the modified microchannels were all studied. The NiO nanosheet array-modified microchannels could almost absorb all of the target proteins when the protein solution (500 μg mL−1) resided in the microchannel for 120 s without separation. The excellent protein absorption ability of NiO nanosheet array-modified microchannels could be attributed to their high zeta potential and more absorption sites induced by the macroporous structure consisting of large nanosheets. Moreover, the NiO nanosheet array-modified microchannels also exhibited excellent selective absorption ability for hemoglobin from a protein mixture and human blood samples owing to the strong affinity interaction between nickel and the histidine residues of hemoglobin. Therefore, the NiO nanosheet array-modified microchannels showed promise for application in proteomics.
Co-reporter:Yuanqiang Wang, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Nanoscale 2015 vol. 7(Issue 14) pp:6185-6192
Publication Date(Web):02 Mar 2015
DOI:10.1039/C4NR06458E
In an aqueous-phase system, AgInS2 quantum dot (QD) sensitized TiO2 photoanodes were prepared in situ by the reaction of β-In2S3 nanocrystals and as-prepared TiO2/Ag2S–QD electrodes, followed by a covering process with a ZnS passivation layer. A facile successive ionic layer adsorption and reaction (SILAR) method was adopted to obtain TiO2/Ag2S–QD electrodes. β-In2S3 nanocrystals synthesized by the chemical bath deposition (CBD) process serve as the reactant of AgInS2 as well as a buffer layer between the interfaces of TiO2 and AgInS2–QDs. A polysulfide electrolyte and a Pt-coated FTO glass count electrode were used to test the photovoltaic performance of the constructed devices. The characteristics of the sensitized photoelectrodes were studied in more detail by electron microscopy, X-ray techniques, and optical and photoelectric performance measurements. AgInS2 is the main photo-sensitizer for TiO2/AgInS2–QD/In2S3 electrodes and excess In2S3 appears on the surface of the electrodes. Based on the optimal Ag2S SILAR cycle, the best photovoltaic performance of the prepared TiO2/AgInS2–QD/In2S3 electrode with the short-circuit photocurrent density (Jsc) of 7.87 mA cm−2 and power conversion efficiency (η) of 0.70% under full one-sun illumination was achieved.
Co-reporter:Gang Wang, Cansheng Yuan, Boyi Fu, Luye He, Elsa Reichmanis, Hongzhi Wang, Qinghong Zhang, and Yaogang Li
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 38) pp:21580
Publication Date(Web):September 9, 2015
DOI:10.1021/acsami.5b06851
Low-cost microfluidic devices are desirable for many chemical processes; however, access to robust, inert, and appropriately structured materials for the inner channel wall is severely limited. Here, the shear force within confined microchannels was tuned through control of reactant solution fluid-flow and shown to dramatically impact nano- through microstructure growth. Combined use of experimental results and simulations allowed controlled growth of 3D networked Zn(OH)F nanostructures with uniform pore distributions and large fluid contact areas on inner microchannel walls. These attributes facilitated subsequent preparation of uniformly distributed Pd and PdPt networks with high structural and chemical stability using a facile, in situ conversion method. The advantageous properties of the microchannel based catalytic system were demonstrated using microwave-assisted continuous-flow coupling as a representative reaction. High conversion rates and good recyclability were obtained. Controlling materials nanostructure via fluid-flow-enhanced growth affords a general strategy to optimize the structure of an inner microchannel wall for desired attributes. The approach provides a promising pathway toward versatile, high-performance, and low-cost microfluidic devices for continuous-flow chemical processes.Keywords: 3D networks; flow chemistry; microfluidic reactions; shear stress
Co-reporter:Jiuke Mu, Chengyi Hou, Hongzhi Wang, Yaogang Li, Qinghong Zhang
Carbon 2015 Volume 95() pp:150-156
Publication Date(Web):December 2015
DOI:10.1016/j.carbon.2015.08.027
Graphene nanosheet devices have attracted significant interest in transistor and photodetector applications owing to photothermoelectric effects of graphene. However, their solar energy conversion ability has not been fully explored due to disadvantages of their transparency and zero gap semiconductor in this special field. Here, we propose the potential of graphene-carbon nanotube papers for energy conversion and storage under sunlight and heat. We show that macroscopic 3-dimensional structure of graphene-carbon nanotube papers provides advantages over graphene nanomaterials in converting large area power sources, namely solar and thermal energy into considerable current and voltage. We also report a graphene-carbon nanotube paper stack with p-n interfaces that incorporates a solar/thermal energy cell and a p–n junction capacitor, which can be simultaneously used for energy conversion and storage with a charge-storage capacity of 70.5 μC cm−2 at one sun intensity.
Co-reporter:Hailun Zong, Jie Zhang, Guoying Shi, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2015 Volume 179() pp:197-205
Publication Date(Web):10 October 2015
DOI:10.1016/j.electacta.2015.03.128
•An alternative way to fabricate DSSC photoanode via liquid phase deposition was presented.•DSSC with TiO2 films first deposited at a higher temperature (80 °C) and subsequently at a lower temperature (60 °C) with an efficiency of 6.51%.•EIS indicated the two-temperature deposited TiO2 film had a lower resistance as well as a longer electronic lifetime.Anatase TiO2 films were directly grown on the conductive glass by liquid phase deposition (LPD) and used as the photoanodes of dye-sensitized solar cells (DSSCs). TiO2 films deposited at a higher temperature had a wider pore size distribution and a perfectly interfacial binding with the conductive FTO layer, while the ones deposited at a lower temperature presented a higher specific surface area to adsorb more dye so that the DSSCs with such two-temperature deposited gradient TiO2 films had the enhanced performance significantly. Moreover, deposition at 80 °C showed a higher deposition rate and TiO2 in the derived films was in a large crystallite size as well as a larger particle size, but a longer duration resulted in some single-crystal particles through the dissolving-precipitation mechanism, which were not suitable to the photoanodes. Thus, gradient TiO2 films were firstly deposited at 80 °C and subsequently at 60 °C for a varying duration to efficiently tune their thickness. The DSSCs with the gradient TiO2 film photoanodes presented a short-circuit current density of 14.9 mA cm−2 and an energy conversion efficiency of 6.51%. For a comparison, LPD TiO2 film without gradient structure was prepared at a fixed temperature (60 °C), which presented a short-circuit current density and photo-to-electric conversion efficiency of 8.78 mA cm−2 and 4.39%, respectively. The electrochemical impedance spectroscopy (EIS) analysis indicated the DSSCs with TiO2 films via two-stage deposition had a lower charge transfer resistance at TiO2/dye/electrolyte interface and a longer electronic lifetime.Gradient TiO2 photoanodes prepared by liquid phase deposition, which gained an efficiency as high as 6.51%.
Co-reporter:Jie Zhang, Yichuan Rui, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2015 Volume 176() pp:480-487
Publication Date(Web):10 September 2015
DOI:10.1016/j.electacta.2015.07.041
•An alternative way to fabricate TiO2 nanocrystals for DSSC photoanode via solid state reaction was presented.•The DSSC with an efficiency of 8.16 % was archived by TiO2 well-connected nanocrystals resulted from the decomposition of (NH4)2TiO(SO4)2.•EIS indicated the well connected TiO2 nanocrystals in DSSCs had a lower resistance.TiO2 nanocrystals derived from hydrothermal method were widely used as the photoanodes of dye-sensitized solar cells (DSSCs). Developing some alternative routes combining low-cost with high performance is eagerly expected. Well connected anatase TiO2 nanocrystals were synthesized by one-step thermal decomposition of the double salt (NH4)2TiO(SO4)2 (ammonium titanyl sulfate, ATS) at 700 °C for 2 h, and the fine tuning on aggregate sizes was achieved by adjusting the heating rate. The TiO2 nanocrystals inside the aggregates were densely packed where each nanocrystal contacted well to neighbouring grains. The connected structure between the crystallites decreases the negative effects of electron grain boundary crossing and reduces recombination within the aggregate when used as photoelectrodes of dye-sensitized solar cells. Moreover, TiO2 aggregates from ATS calcined at a faster heating rate (5 °C/min) had a wider pore size distribution and exhibited a higher light scattering abilities, while the ones from those calcined at a slower heating rate (3 °C/min) had a narrow pore size distribution but possessed a higher specific surface area (72.8 m2 g−1) for adsorbing more dye. The DSSC based on two kind of TiO2 nanoparticles as the photoelectrode all exhibited an excellent short-circuit current density (15.21 mA cm−2 and 15.94 mA cm−2) and a highly efficient power conversion efficiency (7.78% and 8.16%). The improvements of power conversion efficiency for two kinds of TiO2 nanoparticles compared to commercial Aerosil process P25 nanoparticles are mainly attributed to a higher light scattering ability and superior dye adsorption property, respectively. The electrochemical impedance spectroscopy (EIS) analysis indicated the DSSCs with TiO2 nanocrystals derived from solid state reaction had a lower charge transfer resistance than all P25 photoanodes at TiO2/dye/electrolyte interface due to the well connected structure provided multiple contacts to neighboring grains.Well connected anatase TiO2 nanocrystals were synthesized by solid state reaction, which had a lower resistance and their DSSCs gained an efficiency as high as 8.16 %.
Co-reporter:Zhenhua Chen, Xinxin Qin, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Colloid and Interface Science 2015 Volume 459() pp:44-52
Publication Date(Web):1 December 2015
DOI:10.1016/j.jcis.2015.08.008
•Silver colloid solutions with different extinction wavelengths were synthesised.•Ag nanoparticles coated CaTiO3:Eu3+ phosphor was obtained by opposites charge attracting.•Both the PL intensity and heat dissipation of CTOE were enhanced by the Ag coating.•Pc-LED made of Ag-coated CTOE had higher efficiency and more stable working status.Phosphor plays an important role in LEDs—the next generation of lighting source. However, many families of phosphor like titanate still face two severe problems: Low photoluminescence (PL) efficiency and poor thermal stability. Herein, the silver coating is applied to alleviate the above challenges. Ag nanoparticles with different morphology like disks or triangular plates are synthesised by a simple sol-reduction method, and then coated on the shape-regular CaTiO3:Eu (CTOE) phosphor. When the localized surface plasmon resonance (LSPR) extinction spectrum of Ag nanoparticles matches well with excitation or emission wavelength, the PL intensity of CTOE phosphor would be efficiently enhanced. There is an optimum point of LSPR coating amount due to the balance of LSPR-enhancement and scattering/reflection–reduction of Ag nanoparticles. The coating of Ag also leads to an improvement in heat dissipation of CTOE phosphors; meanwhile an overmuch of Ag would also reduce the luminous efficiency. Thus the most suitable coating amount based on the overall consideration successfully enables the enhancement of both PL intensity and heat dissipation, and the pc-LED lamp packaged with Ag coated CTOE phosphor also shows a higher efficiency and more stable working status than the uncoated ones.Ag nanoparticles coated CaTiO3: Eu phosphor obtained from charge attracting process shows higher PL intensity and enhanced heat dissipation than the uncoated ones due to the LSPR effect and heat conduction of Ag nanoparticles, respectively.
Co-reporter:Gang Wang, Zhongyuan He, Guoying Shi, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Journal of Colloid and Interface Science 2015 Volume 446() pp:290-297
Publication Date(Web):15 May 2015
DOI:10.1016/j.jcis.2015.01.048
Glass/silica-based flow channels are widely used in capillary electrophoresis and micro-total analysis systems. However, it is almost impossible to achieve controllable fabrication of microstructures with enhanced mixing performance for high-efficiency bio-analysis in confined micro-channels. Here, various morphologies were controllably achieved by tuning the molar ratio of the reaction agents in a confined microchannel. Fluid flow simulation is demonstrated to investigate the structure stability and mixing performance. Multifunctional networks with uniform and deep decoration are fabricated in confined micro-capillaries, owing to the enhanced mixing performance. The modified micro-capillaries exhibit high efficiencies for the selective enrichment of phosphopeptides from traditional model samples. Furthermore, the fabricated micro-capillaries also exhibited high performance in practical applications (for selective enrichments from bovine milk and cancer serum). These outstanding features make the microstructure-modified micro-capillaries promising for bio-analysis.
Co-reporter:Xuedong Li, Qinghong Zhang, Hognzhi Wang, Yaogang Li
Applied Surface Science 2015 Volume 358(Part A) pp:57-62
Publication Date(Web):15 December 2015
DOI:10.1016/j.apsusc.2015.08.222
Highlights
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(Ga1−xZnx)(N1−xOx)–rGO composite were prepared via hydrothermal and subsequent nitridation.
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(Ga1−xZnx)(N1−xOx)–rGO with a higher specific surface area as well as a finer crystallite size of (Ga1−xZnx)(N1−xOx).
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(Ga1−xZnx)(N1−xOx)–rGO with 4.5 times higher H2 production than bare (Ga1−xZnx)(N1−xOx).
Co-reporter:Dongyu Xu, Yichuan Rui, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Applied Surface Science 2015 Volume 358(Part A) pp:436-442
Publication Date(Web):15 December 2015
DOI:10.1016/j.apsusc.2015.08.160
Highlights
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A facile way to fabricate earth-abundant α-Fe2O3/Zn-Co LDH composite photoanode via electrodeposition was presented.
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The highest photocurrent 1.73 mA/cm2 at 1.23 V vs RHE was achieved by 60 s electrodeposition (i.e., 36% increment).
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EIS indicated the enhanced charge transfer rate comes from improvement of water oxidation.
Co-reporter:Tao Huang, Cheng Wang, Hao Yu, Hongzhi Wang, Qinghong Zhang, Meifang Zhu
Nano Energy 2015 Volume 14() pp:226-235
Publication Date(Web):May 2015
DOI:10.1016/j.nanoen.2015.01.038
•Nanofiber with secondary nanostructures improved the TENG performance.•The piezoelectric effect of PVDF nanofibers has been systematically investigated.•Breathable nanofiber meets the user requirements of flexibility and wearability.•Conductive wearable fabrics further enhanced the output power of the TENG.A simple-to-fabricate, high-performance, wearable all-fiber triboelectric nanogenerator (TENG)-based insole composed of electrospun piezoelectric polyvinylidene fluoride (PVDF) nanofibers sandwiched between a pair of conducting fabric electrodes that effectively harvests energy during human walking is reported. The surface of the nanofibers is roughened with secondary nanostructure to enhance insole performance. The maximum output voltage, instantaneous power and output current from the insole reach 210 V, 2.1 mW and 45 μA, respectively. The role of the piezoelectric effect in the electrospun PVDF nanofibers in this TENG-based insole is then systematically investigated. This device is shown to be a reliable power source that can be used to light up 214 serially connected light-emitting diodes directly. The soft fiber-based electric power generator demonstrated in this paper is capable of meeting the requirements of wearable devices because of its efficient energy-conversion performance, high durability, user comfort, and low cost.
Co-reporter:Guoji Huang, Chengyi Hou, Yuanlong Shao, Bingjie Zhu, Baoping Jia, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Nano Energy 2015 Volume 12() pp:26-32
Publication Date(Web):March 2015
DOI:10.1016/j.nanoen.2014.11.056
•Porous graphene ribbons are continuously fabricated.•The accessible surface area of graphene sheets in electrode are efficiently used.•The supercapacitor with a high performance and long cycling stability is prepared.•The flexible supercapacitors can be weaved into a glove and bent.Porous graphene ribbons are continuously fabricated and used as electrodes in all-solid-state supercapacitors. Their unique structure effectively prevents the inter-sheet restacking of graphene sheets and fully exploits the large surface area of graphene sheets for energy storage. The resultant symmetric all-solid-state yarn supercapacitor has a high specific capacitance of 208.7 F/g (78.3 mF/cm2 or 3.12 mF/cm) and a high cycling stability (99% capacitance retention after 5000 cycles). Furthermore, the supercapacitor is flexible and its performance is only reduced by 5% after 100 bending cycles when weaved into a glove.
Co-reporter:Fuzhi Shi;Jin Liu;Bo Cui;Yaogang Li;Qinghong Zhang
Ionics 2015 Volume 21( Issue 3) pp:651-656
Publication Date(Web):2015 March
DOI:10.1007/s11581-014-1232-y
Olivine-structured LiMnPO4-MWCNT cathode materials are fabricated via vapor phase hydrolysis without calcination process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm analysis, galvanostatic charging-discharging test, and electrochemical impedance spectroscopy (EIS). All XRD results show LiMnPO4 and multi-walled carbon nanotubes (MWCNTs) coexisted in the obtained sample. The appropriate temperature to synthesize LiMnPO4 cathode material is 200 °C, and MWCNT addition accelerates growing of (020) plane. SEM shows MWCNTs have been coated onto the surface of LiMnPO4 and the morphology of LiMnPO4 can be tuned from fragment to long strip by varying MWCNT contents. EIS results indicate that MWCNTs are able to accelerate the diffusion of Li+ ion across LiMnPO4-MnPO4 boundary, so galvanostatic charging-discharging test indicates that the initial capacity of LiMnPO4-MWCNT composites is higher than that of LiMnPO4. The best initial discharge capacity is 113 mAh/g (0.1 C) when MWCNT addition is 5 % due to the synthetic effect of improved electrochemical performance and relatively small dimensions.
Co-reporter:Jiuke Mu;Chengyi Hou;Yaogang Li;Qinghong Zhang;Meifang Zhu
Science Advances 2015 Volume 1(Issue 10) pp:e1500533
Publication Date(Web):06 Nov 2015
DOI:10.1126/sciadv.1500533
Origami-inspired self-folding graphene papers show remote control grasping, manipulation, and walking behaviors.
Co-reporter:Gang Wang, Nils Persson, Ping-Hsun Chu, Nabil Kleinhenz, Boyi Fu, Mincheol Chang, Nabankur Deb, Yimin Mao, Hongzhi Wang, Martha A. Grover, and Elsa Reichmanis
ACS Nano 2015 Volume 9(Issue 8) pp:8220
Publication Date(Web):July 16, 2015
DOI:10.1021/acsnano.5b02582
Very few studies have reported oriented crystallization of conjugated polymers directly in solution. Here, solution crystallization of conjugated polymers in a microfluidic system is found to produce tightly π-stacked fibers with commensurate improved charge transport characteristics. For poly(3-hexylthiophene) (P3HT) films, processing under flow caused exciton bandwidth to decrease from 140 to 25 meV, π–π stacking distance to decrease from 3.93 to 3.72 Å and hole mobility to increase from an average of 0.013 to 0.16 cm2 V–1 s–1, vs films spin-coated from pristine, untreated solutions. Variation of the flow rate affected thin-film structure and properties, with an intermediate flow rate of 0.25 m s–1 yielding the optimal π–π stacking distance and mobility. The flow process included sequential cooling followed by low-dose ultraviolet irradiation that promoted growth of conjugated polymer fibers. Image analysis coupled with mechanistic interpretation supports the supposition that “tie chains” provide for charge transport pathways between nanoaggregated structures. The “microfluidic flow enhanced semiconducting polymer crystal engineering” was also successfully applied to a representative electron transport polymer and a nonhalogenated solvent. The process can be applied as a general strategy and is expected to facilitate the fabrication of high-performance electrically active polymer devices.Keywords: charge transport mobility; conjugated polymer; crystal engineering; microfluidic; tie-chains;
Co-reporter:Guang Liu, Zifeng Tian, Zhenhua Chen, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Optical Materials 2015 40() pp: 63-67
Publication Date(Web):
DOI:10.1016/j.optmat.2014.11.047
Co-reporter:Chengyi Hou;Qinghong Zhang;Yaogang Li;Meifang Zhu
Advanced Materials 2014 Volume 26( Issue 29) pp:5018-5024
Publication Date(Web):
DOI:10.1002/adma.201401367
Co-reporter:Gang Wang;Guoying Shi;Qinghong Zhang;Yaogang Li
Advanced Functional Materials 2014 Volume 24( Issue 7) pp:1017-1026
Publication Date(Web):
DOI:10.1002/adfm.201301936
Construction of stable 3D networks directly on the inner wall of microchannels is of great importance for various microfluidic applications. 3D nest-like networks with large contact surface areas and excellent structural stability are fabricated via a facile, template-free, continuous fluid construction process directly in confined microchannels. Bovine serum albumin (BSA) is chosen as a model albumin to test the adsorption of the network modified microchannel to the target albumin. The high structural stability of the networks is confirmed both by finite element analysis (FEA) simulation and recycling experiments for BSA enrichment. ZnS shells are fabricated based on the original 3D Zn(OH)F networks through in situ chemical conversion. The nest-like networks decorated with Ag nanoparticles (NPs) serve as 3D substrates for surface-enhanced Raman scattering (SERS), exhibiting excellent sensitivity for rapid detection of trace 10−12 mol L−1 (1 pM) BSA. Three different gap sizes between Ag NPs in the 3D geometry create a large number of SERS hot spots that contribute to the high sensitivity of the networks. Furthermore, a transparent, flexible, microfluidic device containing the 3D nest-like structures exhibits excellent recyclability and flexible stability for trace BSA enrichment, showing potential for application in online SERS detection.
Co-reporter:Yuanlong Shao, Hongzhi Wang, Qinghong Zhang and Yaogang Li
NPG Asia Materials 2014 6(8) pp:e119
Publication Date(Web):2014-08-01
DOI:10.1038/am.2014.59
Graphene, the last representative sp2 carbon material to be isolated, acts as an ideal material platform for constructing flexible electronic devices. Exploring a new method to fabricate high-quality graphene films with high throughput is essential for achieving greater performance with flexible electronic devices. Here, we report a facile coating and subsequent illumination method for mass-fabricating highly crystalline photoreduced graphene oxide (PRGO) films directly onto conductive substrates. The direct fabrication of PRGO films onto Cu foils with partial oxygenated groups, an intensive stacked highly crystalline structure, and reduced graphene oxide regions enable significant performance enhancements when used as supercapacitor electrodes compared with other graphene-only devices, exhibiting high specific capacitances of 275 F g−1 at a scan rate of 10 mV s−1 and 167 F g−1 at 1 V g−1 with excellent rate capability. The as-established all-solid-state flexible supercapacitors exhibit superior flexibility and robust mechanical stability, resulting in a capacitance delay of only 2% after performing 100 bending cycles. The demonstrated PRGO films provide a promising material platform to realize a broad range of applications related to flexible electronics devices.
Co-reporter:Dongyun Ma, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 33) pp:13541-13549
Publication Date(Web):10 Jun 2014
DOI:10.1039/C4TA01722F
The high performance of organic/inorganic hybrid materials relies largely on a scrupulous design of nanoarchitectures so that the organic and inorganic phases can work synergistically. We present a powerful two-step solution-based method for the fabrication of hierarchical metal oxide/conducting polymer heterostructured nanoarrays. Demonstrated examples include different nanostructures (nanorod arrays, nanorod-based networks and nanoplate arrays) of metal oxides (WO3 and NiO) and PANI (nanostubs, nanoparticles and nano-wrinkles). Given the unique composition and architecture, the hierarchical NiO/PANI nanoplate arrays show reversible multicolor changes, fast switching speeds of 90 and 120 ms for coloration and bleaching states, respectively, and a superior coloration efficiency of 121.6 cm2 C−1 under a low voltage of 1.2 V. Additionally, the application of the NiO/PANI nanoplate array coated FTO glass causes a temperature difference of 7–7.6 °C under different ambient temperatures, making it very attractive for potential applications in energy-saving smart windows. Our strategy paves the way for the design and synthesis of hierarchical metal oxide/conducting polymer nanoarrays with enhanced properties for new applications.
Co-reporter:Haizeng Li, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 29) pp:11305-11310
Publication Date(Web):21 May 2014
DOI:10.1039/C4TA01803F
Self-seeded hydrothermal process could eliminate the grain boundaries existing in the nanocrystalline base layer, which speeds up electron transport to the fluorine-doped tin oxide (FTO) glass and promotes electron transfer efficiency. This report highlights the hierarchical nest-like WO3·0.33H2O film grown directly on bare FTO glass without a seed layer prepared in advance. The film exhibits highly improved electrochromic performances.
Co-reporter:Sujun Yuan, Jiuke Mu, Ruiyi Mao, Yaogang Li, Qinghong Zhang, and Hongzhi Wang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 8) pp:5719
Publication Date(Web):March 26, 2014
DOI:10.1021/am500314n
The multilaminated ZnO/TiO2 heterojunction films were successfully deposited on conductive substrates including fluorine-doped tin oxide (FTO) glass and flexible indium tin oxide coated poly(ethylene terephthalate) via the layer-by-layer (LBL) self assembly method from the oxide colloids without using any polyelectrolytes. The positively charged ZnO nanoparticles and the negatively charged TiO2 nanoparticles were directly used as the components in the consecutive deposition process to prepare the heterojunction thin films by varying the thicknesses. Moreover, the crystal growth of both oxides could be efficiently inhibited by the good connection between ZnO and TiO2 nanoparticles even after calcination at 500 °C, especially for ZnO which was able to keep the crystallite size under 25 nm. The as-prepared films were used as the working electrodes in the three-electrode photoelectrochemical cells. Because the well-contacted nanoscale heterojunctions were formed during the LBL self-assembling process, the ZnO/TiO2 all-nanoparticle films deposited on both substrates showed remarkably enhanced photoelectrochemical properties compared to that of the well-established TiO2 LBL thin films with similar thicknesses. The photocurrent response collected from the ZnO/TiO2 electrode on the FTO glass substrate was about five times higher than that collected from the TiO2 electrode. Owing to the absence of the insulating layer of dried polyelectrolytes, the ZnO/TiO2 all-nanoparticle heterojunction films were expected to be used in the photoelectrochemical device before calcination.Keywords: all-nanoparticle; heterojunction; layer-by-layer self-assembly; photoelectrochemical; titania; zinc oxide;
Co-reporter:Kerui Li, Qinghong Zhang, Hongzhi Wang, and Yaogang Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:13043
Publication Date(Web):July 24, 2014
DOI:10.1021/am502929p
These fibers are prepared using stainless steel wires (SSWs) as a substrate. Three kinds of electrochromic materials (poly(3,4-ethylenedioxythiophene), poly(3-methylthiophene), and poly(2,5-dimethoxyaniline)) are quickly deposited on the surface of the SSWs by electrochemical polymerization. A polymer gel electrolyte is then coated onto the electrochromic layer, and another finer stainless steel wire is twisted on, in succession. The obvious RGB colors and gradient color phenomenon from gray to dark blue are observed by the naked eye besides color changes from oxidized to reduced states. Moreover, these electrochromic fibers have very short response times (millisecond scale), excellent flexibility, and good structural stability even though the bending and folding occurred. They also can be implanted into fabrics to achieve more color combinations through regulating the voltages and parallel connection of different circuits.Keywords: electrochromic fibers; gradient color phenomenon; smart fabrics; three complementary colors; π-conjugated organic polymers
Co-reporter:Yanmin Hao, Yichuan Rui, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2014 Volume 117() pp:268-275
Publication Date(Web):20 January 2014
DOI:10.1016/j.electacta.2013.11.128
•The anatase TiO2 sol with a crystallite size of 3.0 nm was prepared.•Both TiO2 sol and titanium (IV) bis (ammonium lactato) dihydroxide were successfully used towards size-tunable anatase TiO2 nanocrystals.•The DSSC with an efficiency of 9.3% was archived by combining of TiO2 nanocrystals and sol treatment.•Improved interfacial contact was responsible to the performance enhancement of DSSCs.Titanium (IV) bis (ammonium lactato) dihydroxide (TALH) was employed to prepare anatase TiO2 sol where titania in a crystallite size of 3 nm. Both the sol and TALH solution were further subjected to be hydrothermal treated at 200 °C to grow the crystallite size be most appropriate for the photoanodes of dye-sensitized solar cells (DSSCs). The DSSCs with photoanodes derived from the sol-hydrothermal TiO2 exhibited the overall energy conversion efficiency (η) of 7.8%, while the DSSCs with photoanodes derived from the TALH direct hydrothermal (DH) showed a higher η of 8.9%. Moreover, the as-prepared anatase TiO2 sol prior to the hydrothermal treatment was used as substitute for TiCl4 solution to modify the porous DH TiO2 photoanodes, and the DSSCs achieved overall energy conversion efficiency as high as of 9.3%, due to the extremely fine anatase nanocrystals in the TiO2 sol improved the connection between the TiO2 nanocrystals more significantly compared to the TiCl4 treatment.TiO2 nanocrystals derived from aqueous TALH were fabricated as the photoanodes of DSSCs, which gained efficiency as high as 9.3%.
Co-reporter:Li Zhang, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Applied Surface Science 2014 Volume 319() pp:21-28
Publication Date(Web):15 November 2014
DOI:10.1016/j.apsusc.2014.07.199
Highlights
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TiO2/SnO2 heterojunctions formed between oxide fibers in the side-by-side structure with Pt nanocrystals in a crystallite size of 4.5 nm uniformly deposited on them.
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Pt-TiO2/SnO2 nanofibers possessed large surface-exposure area, broadened spectral response range, stable recyclability, and efficient charge-separation properties, resulting in their efficient photocatalytic activity.
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The results demonstrated the heterostructured materials as high-performance photocatalysts and their potential use in environmental protection.
Co-reporter:Mengyu Gao ; Yichuan Rui ; Hongzhi Wang ; Yaogang Li ;Qinghong Zhang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 30) pp:16951-16958
Publication Date(Web):March 17, 2014
DOI:10.1021/jp500466s
Submicrometer@nano bimodal TiO2 particles consisting of a submicrometer core and a mesoporous structured shell were synthesized by a chemical deposited method. The submicrometer TiO2 particles were first dispersed in the titanium(IV) bis(ammonium lactato) dihydroxide solution in the presence of polyethyleneimine and urea; after reflowing hydrolysis, the suspension was transferred to a Teflon autoclave and subjected to hydrothermal treatment at 150 °C for 24 h. The as-prepared nanocrystal-coated submicrometer TiO2 (NCS-TiO2) showed a core/shell structure where the outer TiO2 nanocrystals with the size of 5 to 7 nm and in anatase phase uniformly coated on the submicrometer TiO2. When the NCS-TiO2 was fabricated as the scattering layer in dye-sensitized solar cells (DSSCs), it adsorbed more dye molecules while still keeping a high light-harvesting efficiency. Moreover, the presence of TiO2 nanocrystals in NCS-TiO2 reduced the sintering stress between the transparent porous layer and the scattering layer, leading to a crack-free and high-quality photoanode film, which also reduced the serial resistance, as verified by electrochemical impedance spectroscopy. Finally, DSSCs with the NCS-TiO2 scattering layer reached an efficiency of 8.36%, which showed a 20% improvement compared with the one without it.
Co-reporter:Dongchen Che, Xiaoxu Zhu, Peifeng Liu, Yourong Duan, Hongzhi Wang, Qinghong Zhang, Yaogang Li
Journal of Luminescence 2014 153() pp: 369-374
Publication Date(Web):
DOI:10.1016/j.jlumin.2014.03.028
Co-reporter:Yichuan Rui, Yaogang Li, Qinghong Zhang and Hongzhi Wang
Nanoscale 2013 vol. 5(Issue 24) pp:12574-12581
Publication Date(Web):30 Sep 2013
DOI:10.1039/C3NR04462A
TiO2 microspheres assembled by single crystalline rutile TiO2 nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous–organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 μm by adjusting the volume of the reactant water. Nitrogen adsorption–desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m2 g−1. The 1 μm sized TiO2 nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO2. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.
Co-reporter:Yuanlong Shao, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:1245-1251
Publication Date(Web):05 Dec 2012
DOI:10.1039/C2TC00235C
We demonstrate a simple method for preparing flexible, free-standing, three-dimensional porous graphene/MnO2 nanorod and graphene/Ag hybrid thin-film electrodes using a filtration assembly process. These graphene hybrid films, which accelerate ion and electron transport by providing lower ion-transport resistances and shorter diffusion-distances, exhibit high specific capacitances and power performances, and excellent mechanical flexibility. A novel asymmetric supercapacitor (SC) has been fabricated by using a graphene/MnO2 nanorod thin film as the positive electrode and a graphene/Ag thin film as the negative electrode. These devices exhibit a maximum energy density of 50.8 W h kg−1 and present a high power density of 90.3 kW kg−1, even at an energy density of 7.53 W h kg−1. The bent hybrid nanostructured asymmetric SC is connected to spin a fan, which also proved the high power density of the fabricated asymmetric SCs. These results suggest that such asymmetric graphene/MnO2 nanorod and graphene/Ag hybrid thin-film architectures are promising for next-generation high-performance flexible supercapacitors.
Co-reporter:Dongyun Ma, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 3) pp:684-691
Publication Date(Web):22 Oct 2012
DOI:10.1039/C2TA00090C
We have demonstrated that vertically aligned WO3 nanostructure films can be fabricated on FTO-coated glass substrates using a template-free hydrothermal technique. Detailed mechanistic studies revealed that a variety of WO3 nanostructures—including nano-bricks, 1D nanorods and nanowires, and 3D nanorod-flowers—could be obtained by tuning the composition of the precursor solution, where the urea content and solvent composition played important roles in controlling the shape and size of the WO3 nanostructures, respectively. These nanostructured films exhibited enhanced electrochromic performance, and we drew a map for the correlation between the morphology and the electrochromic performance of the as-synthesized WO3 films. Due to the large tunnels in the hexagonally structured WO3, and the large active surface area available for electrochemical reactions, a large optical modulation of 66% at 632.8 nm and a potential of −2.0 V, fast switching speeds of 6.7 s and 3.4 s for coloration and bleaching, respectively, and a high coloration efficiency of 106.8 cm2 C−1 are achieved for the cylindrical nanorod array film.
Co-reporter:Yuan-qiang Wang, Yi-chuan Rui, Qing-hong Zhang, Yao-gang Li, and Hong-zhi Wang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 22) pp:11858
Publication Date(Web):October 25, 2013
DOI:10.1021/am403555c
CuInS2 quantum-dot sensitized TiO2 photoanodes with In2S3 buffer layer were in situ prepared via chemical bath deposition of In2S3, where the Cd-free In2S3 layer then reacted with TiO2/CuxS which employed a facile SILAR process to deposit CuxS quantum dots on TiO2 film, followed by a covering process with ZnS layer. Polysulfide electrolyte and Cu2S on FTO glass counter electrode were used to provide higher photovoltaic performance of the constructed devices. The characteristics of the quantum dots sensitized solar cells were studied in more detail by optical measurements, photocurrent–voltage performance measurements, and impedance spectroscopy. On the basis of optimal CuxS SILAR cycles, the best photovoltaic performance with power conversion efficiency (η) of 1.62% (Jsc = 6.49 mA cm–2, Voc = 0.50 V, FF = 0.50) under full one-sun illumination was achieved by using Cu2S counter electrode. Cu2S-FTO electrode exhibits superior electrocatalytic ability for the polysulfide redox reactions relative to that of Pt-FTO electrode.Keywords: Cu2S counter electrode; CuInS2; CuxS quantum dots; In2S3 buffer layer; quantum-dot sensitized TiO2 photoanodes;
Co-reporter:Li Zhang, Yaogang Li, Qinghong Zhang and Hongzhi Wang
CrystEngComm 2013 vol. 15(Issue 30) pp:5986-5993
Publication Date(Web):17 May 2013
DOI:10.1039/C3CE40620B
A hierarchically nanostructured TiO2/WO3 photocatalyst was synthesized via the subsequent hydrothermal treatment of electrospun TiO2 nanofibers in the presence of tungstic acid. With a uniform WO3 seed layer providing growth sites, the nucleation on the nanofibers was uniform, thus uniform WO3 nanorods could be grown. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectra (PL), and Brunauer–Emmett–Teller (BET) method. The results indicated that the WO3 nanorods with a diameter of about 40 nm and an average length of about 150 nm grew perpendicularly on the TiO2 nanofibers. The crystallite size and specific surface area of the bare TiO2 nanofibers were about 30 nm and 46.5 m2 g−1. The bare nanofibers are anatase phase with the average diameter of about 350 nm. The TiO2/WO3 heterostructures provide more accessible sites for both catalysis and adsorption, and the WO3 nanorods possess a single crystal structure, which facilitates the migration of the photogenerated electrons. Photocatalytic tests show that the TiO2/WO3 heterostructures exhibit a remarkably higher degradation rate of organic pollutants than that of the bare TiO2 nanofibers under visible light irradiation. The enhanced photocatalytic activity is attributed to the extended absorption in the visible light region and the effective charge separation derived from the coupling effect of TiO2 and WO3 nanocomposites.
Co-reporter:Yichuan Rui, Yaogang Li, Qinghong Zhang and Hongzhi Wang
CrystEngComm 2013 vol. 15(Issue 8) pp:1651-1656
Publication Date(Web):17 Dec 2012
DOI:10.1039/C2CE26691A
Sub-micrometer sized rutile TiO2 nanorod microspheres with diameters of 500–700 nm and with a specific surface area of 63.7 m2 g−1 were synthesized via a salt-assisted hydrothermal method. Morphological evolution as a function of reaction time was carried out to gain insight into the formation mechanism of the nanorod microspheres. Unlike traditional bulk rutile TiO2 particles, the nanorod microspheres could provide dual-functions of adsorbing dye molecules and strong light-harvesting efficiency when they were fabricated as a scattering overlayer in dye-sensitized solar cells (DSSCs). Furthermore, the inherent nanorods would provide excellent electron percolation pathways for charge transfer as confirmed by electrochemical impedance spectroscopy. Consequentially, DSSC with the scattering overlayer exhibited a 39% increment of cell efficiency (7.32%) compared with the DSSC without one (5.28%), and the efficiency was also a little higher than the DSSC with the same thickness composed of only nanocrystallites (7.14%).
Co-reporter:Li Zhang, Yaogang Li, Qinghong Zhang and Hongzhi Wang
CrystEngComm 2013 vol. 15(Issue 8) pp:1607-1612
Publication Date(Web):10 Dec 2012
DOI:10.1039/C2CE26758F
This paper reports a facile method for preparation of modified ultrafine anatase titanium dioxide (TiO2) nanoparticles using the hybrid nanofiber as a microsized reactor. The hybrid nanofibers comprised of poly(vinyl pyrolidone) (PVP) and amorphous TiO2 nanoparticles were prepared via the electrospinning method. When the hybrid nanofibers were treated with water vapor at a temperature of 80 °C or above, the nanofibers acted as microsized reactors in which the amorphous TiO2 nanoparticles grew and crystallized into ultrafine anatase TiO2 nanoparticles. The PVP matrix in this microsized reactor could be regarded as a substrate for the reaction and protected the over-growth of the TiO2 nanoparticles during the reaction. Morphological and structural characteristics of the hybrid nanofibers and TiO2 nanoparticles were studied with scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) method, Raman spectroscopy, X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric (TG) analysis. The anatase TiO2 nanoparticles were modified with PVP molecules during the crystallization process, and are expected to be easily mixed with other polymers to fabricate functional textiles.
Co-reporter:Zhifu Liu, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Journal of Colloid and Interface Science 2013 Volume 406() pp:18-23
Publication Date(Web):15 September 2013
DOI:10.1016/j.jcis.2013.05.057
•The structural colored fiber was prepared by a magnetic field induced photopolymerization method.•Long-range one-dimensional superparamagnetic chains were formed in PEGDA resin.•The structural colors (blue, green, and red) were generated instantaneously in micro-space.•This process may have great potential for development in the actual fiber dyeing process.A new type of photonic crystal structural colored fiber was prepared by assembling superparamagnetic chains on the surface of a flexible fiber in a magnetic field under photopolymerization. In this system, fixed structural colors (blue, green, and red) were generated instantaneously. The fiber with multi-stopband can also be prepared by carefully controlling the size of the magnetic spheres in each photopolymerization procedure. This method would be fast and facile for the further study of structural color on the surface of the fiber, and the process may be used to simulate the conventional fiber coloration process.Graphical abstract
Co-reporter:Haocheng Quan, Yuanlong Shao, Chengyi Hou, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Materials Science and Engineering: B 2013 Volume 178(Issue 11) pp:769-774
Publication Date(Web):20 June 2013
DOI:10.1016/j.mseb.2013.03.004
•3D Ag-graphene hybrid hydrogels were prepared at room-temperature.•Symmetric supercapacitors were fabricated based on the hybrid hydrogels.•3D Ag-graphene hybrid hydrogels show superior electrical performance.In this article, we report a room-temperature synthesis of 3-dimentional (3D) Ag-graphene hybrid hydrogels and fabricate a symmetric supercapacitor with this hybrid material. The preparation of this 3D Ag-graphene hybrid hydrogel is facile and its application in macroscopic devices is more convenient than 2-dimentional (2D) graphene-based material. Our work may provide new insights into the room-temperature synthesis of graphene-based materials. In this novel 3D graphene-based material, the unique structure and combination with Ag nanoparticles made this material exhibit better electrochemical performance compared with the pure graphene. Thus, the obtained Ag-graphene hybrid hydorgels could be widely used in various energy storage devices.
Co-reporter:Dongyun Ma, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 32) pp:16633-16639
Publication Date(Web):03 Jul 2012
DOI:10.1039/C2JM32784H
Vertically oriented WO3 nanoflakes woven from nanowires were obtained using a crystal-seed-assisted hydrothermal technique on a glass substrate coated with fluorine-doped tin oxide (FTO). Investigation of the growth process revealed that two types of nanowire, along the (100) and (002) planes, respectively, were formed in the early stages. In the presence of oxalic acid and urea, these nanowires were then interwoven to give a flake-like nanofabric. This process is similar to weaving on a loom, in which the two types of nanowire act as “warp and weft threads” and the oxalic acid and urea act as the “shuttle”. The as-prepared films exhibit tunable transmittance modulation under different voltages, and repeated cycling between the coloration and bleaching states has no deleterious effect on their electrochromic performance after 1000 cycles. A larger optical modulation of 68% at 632.8 nm at a potential of −3.0 V, faster switching speeds of tc(90%) = 9.3 s and tb(90%) = 5.7 s for coloration and bleaching, respectively, and a higher coloration efficiency of 134.4 cm2 C−1 than those previously reported for the electrochromic performances of nanostructured films were achieved for this self-weaving nanoflake film.
Co-reporter:Chengyi Hou, Yourong Duan, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 30) pp:14991-14996
Publication Date(Web):28 May 2012
DOI:10.1039/C2JM32255B
For biomimetic applications, an artificial material is needed to be self-healing, electroactive and bio-applicable. Herein we report a strategy to build a graphene–poly(N,N-dimethylacrylamide) (PDMAA) cross-linking structure based on graphene networks. The obtained hydrogel exhibits good neural compatibility, high conductivity, low impedance and efficient near-infrared-triggered photothermal self-healing behaviour owing to its unique 3-dimensional graphene–PDMAA cross-linking networks. The results indicate that the graphene–PDMAA hydrogel has potential for application as an artificial tissue.
Co-reporter:Chengyi Hou, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Carbon 2012 Volume 50(Issue 5) pp:1959-1965
Publication Date(Web):April 2012
DOI:10.1016/j.carbon.2011.12.049
The reversible stimulus-responsive volume change in graphene materials has never been realized, due to the irreversible restacking or agglomeration of graphene sheets. In this study, the graphene–polymer hydrogel with reversible volume changes has been prepared by a hydrothermal method. It has good electrical conductivity, high mechanical strength and a tunable electrical conductivity. The hydrogel exhibits reversible volume changes in response to an electric current, which makes it a potential candidate for artificial muscle devices.
Co-reporter:Sujun Yuan, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2012 Volume 79() pp:182-188
Publication Date(Web):30 September 2012
DOI:10.1016/j.electacta.2012.06.104
An anatase TiO2 sol containing ultrafine TiO2 crystallites (ca. 5 nm) was used to fabricate the dye-sensitized solar cells (DSSCs) with a compact layer, which was prepared by the peptization–hydrothermal method using the CF3COOH as peptizing agent. The dried sol was calcined at 300 °C for 1 h to eliminate the organics over the surface of TiO2 and increase the crystallite size of the TiO2 nanocrystals (the special surface area of the calcined TiO2 decreased from 224.7 to 94.9 m2/g); and then it was used to prepare the paste for the porous layer of DSSCs. The compact layer was prepared by the diluted sol through the layer-by-layer (LBL) self assembly technique to control its thickness. The compact films derived from LBL self assembly method not only prevented the charge recombination at the conductor substrate/electrolyte interface but also improved the adhesion between the porous layer and the conductive layer on the substrate, which increased the number of the effective electron pathways with the short distance of the porous layer and consequently resulted in a better electrical contact. The photoelectron conversion efficiency of the DSSCs with the LBL films had increased apparently. In particular, a 12-layer TiO2/PSS LBL film of the DSSC led to a 24.5% increase in the photoelectron conversion efficiency from 5.93 to 7.38%.Graphical abstractHighlights► The nanoparticles in anatase TiO2 sol were ultrafine, uniform sized and highly dispersed. ► The compact layer was prepared by LBL self assembly method, which was dense and comparable to that from physical route. ► The 12-layer LBL film of the DSSC led to a 24.5% increment in the conversion efficiency. ► Both porous layer and the compact layer of the DSSCs were derived from the anatase sol.
Co-reporter:Qinghui Mu, Yaogang Li, Hongzhi Wang, Qinghong Zhang
Journal of Colloid and Interface Science 2012 Volume 365(Issue 1) pp:308-313
Publication Date(Web):1 January 2012
DOI:10.1016/j.jcis.2011.09.027
Herein we report the direct fabrication of TiO2 subwavelength structures with 1-dimensional TiO2 nanorods on glass substrate through solvothermal process to form self-cleaning antireflection coatings. TiO2 precursor solutions with different solvent constituents create TiO2 nanorods with much different morphologies grown on glass substrates. Apiculate TiO2 nanorods with vertical orientation are grown on the glass substrate which is solvothermally treated in the precursor solution containing ethylene glycol. This glass substrate exhibit the highest transmittance of 70–85% in the range of 520–800 nm and negligible absorption in visible light region (400–800 nm). Furthermore, the TiO2 nanorod arrays show high hydrophobicity and photocatalytic degradation ability which offer the glass substrate self-cleaning properties for both hydrophilic and oily contaminants.Graphical abstractTiO2 nanorod arrays with different morphologies and structures were successfully synthesized on glass substrate by a facile solvothermal process.Highlights► A sample method was used to fabricate TiO2 nanorod arrays on glass substrate. ► Nanorod arrays with different morphology and structure were obtained. ► Hydrophobic and photocatalytic properties resulted in self-cleaning performance.
Co-reporter:Zhifu Liu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Physics and Chemistry of Solids 2012 Volume 73(Issue 5) pp:651-655
Publication Date(Web):May 2012
DOI:10.1016/j.jpcs.2012.01.003
Pencil-like ZnO microrods was synthesized via a simple solvothermal process in an aqueous solution of ethylenediamine and ethanolamine. The as-prepared ZnO was characterized by X-ray powder diffraction, field-emission scanning electron microscopy, room temperature photoluminescence spectra and UV–vis absorption spectra. The results indicated that ZnO microrods had the length in the range of 1.3–25 μm. The photocatalytic activity was studied by degradation of methylene blue (MB) aqueous solution, which showed that the as-prepared ZnO microrods possessed a high photocatalytic activity. The formation mechanism of the pencil-like ZnO was also investigated based on the experimental results.Highlights► Pencil-like ZnO was synthesized via a solvothermal process in an aqueous solution of EDA-EA. ► Possible growth mechanisms have been proposed by a single-nucleus growth process. ► Photocatalytic properties of ZnO was studied, which was well matched with the case of P25.
Co-reporter:Fei Zhang, Chengyi Hou, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Materials Chemistry and Physics 2012 Volume 135(2–3) pp:826-831
Publication Date(Web):15 August 2012
DOI:10.1016/j.matchemphys.2012.05.065
The production of clean and renewable hydrogen through the hydrolysis of sodium borohydride has received much attention owing to increasing global energy demands. Graphene sheets/cobalt (GRs/Co) nanocomposites, which are highly efficient catalysts, have been prepared using a one-step solvothermal method in ethylene glycol. Co2+ salts were converted to Co nanoparticles, which were simultaneously inserted into the graphene layers with the reduction of graphite oxide sheets to GRs. The as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value reached 80.8 emu g−1, meaning they are more suitable for magnet-controlled generation of H2 than noble metal catalysts. The catalytic activity of the composite was investigated by the hydrolysis of sodium borohydride in aqueous solution both with and without a GRs support. It was found that the high electronic conductive GRs support increased the hydrogen generation rate (about two times) compared with pure cobalt. The improved hydrogen generation rate, low cost and uncomplicated recycling makes the GRs/Co nanocomposites promising candidates as catalysts for hydrogen generation.Graphical abstractHighlights► Graphene sheets/cobalt nanocomposites were prepared by a one-step solvothermal method. ► The maximum saturation magnetization value of the composites reached 80.8 emu g−1. ► The graphene support greatly increased the catalytic activity of cobalt. ► An easily removed, recycled and controlled functional filter was obtained.
Co-reporter:Ya Tang, Xinwei Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Synthetic Metals 2012 Volume 162(3–4) pp:309-313
Publication Date(Web):March 2012
DOI:10.1016/j.synthmet.2011.12.011
Composite nanofibers with a high Co0.8Ni0.2Fe2O4 nano-particulate content were fabricated by electrospinning. Silane coupling agent modified magnetic nanoparticles were directly dispersed in polyvinylpyrrolidone (PVP) solution at a mass ratio of 3:1. The surface morphologies and structures of the resulting nanofibers were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). FESEM and TEM results showed that the average diameter of the composite nanofibers was 350 ± 30 nm and the modified magnetic nanoparticles were evenly dispersed in polymer matrix. VSM results showed that the saturation magnetization of the composite nanofibers was up to 29.8 emu/g and that the fibers also demonstrated superparamagnetic behavior.Highlights► Composite nanofibers with high Co0.8Ni0.2Fe2O4 NPs contents were prepared by ES. ► Composite nanofibers have a narrow size distribution and evenly particles dispersion. ► Composite nanofibers demonstrated a superparamagnetic behavior.
Co-reporter:Xiaoli Miao, Meifang Zhu, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Progress in Natural Science: Materials International 2012 Volume 22(Issue 2) pp:94-99
Publication Date(Web):April 2012
DOI:10.1016/j.pnsc.2012.03.006
The mechanical properties of dental composites were improved by porous diatomite and nano-sized silica (OX-50) used as co-fillers. The resin composites, filled with silanized OX-50 and silanized diatomite (40:60 wt/wt), presented the best flexural strength (133.1 MPa), elastic modulus (9.5 GPa) and Vickers microhardness (104.0 HV). Besides these, TiO2 nanoparticles were introduced to tune the dental resin composites colours which were valued by the CIE-Lab system. The colour parameters (L⁎, a⁎, b⁎) showed that the colour changes of resin composites could be perceived obviously, when 300–400 nm TiO2 particles were introduced as fillers. The resin composite, filled with 0.5 wt% TiO2, exhibited both clear discolouration (ΔE⁎=3.22) and high mechanical strength. Using scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX), the titanium elemental mapping results indicated that the TiO2 particles were distributed evenly in the prepared dental composites.
Co-reporter:Guodong Liu, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Materials Science and Engineering: B 2012 Volume 177(Issue 3) pp:316-320
Publication Date(Web):25 February 2012
DOI:10.1016/j.mseb.2011.12.045
Co-reporter:Ya Tang, Xinwei Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Progress in Natural Science: Materials International 2012 Volume 22(Issue 1) pp:53-58
Publication Date(Web):February 2012
DOI:10.1016/j.pnsc.2011.12.009
Magnetic Co1−xNixFe2O4 nanoparticles (NPs) were successfully synthesized via a solvothermal method using ethylene glycol as solvent. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and gas sensing test. The experimental results showed that the magnetic Co1−xNixFe2O4 NPs were composed of single phase spinel structure and the average crystallite size in the NPs is between 5.8 and 9.8 nm; the NPs are spherical with an average particle size of about 40–90 nm; the saturation magnetization (Ms) of the Co1−xNixFe2O4 NPs decreased linearly as the contents of Ni2+ increased; and the as-prepared Co1−xNixFe2O4 NPs have a higher selectivity toward ammonia vapors and the Co0.8Ni0.2Fe2O4 has the best gas sensitivity of Co1−xNixFe2O4 (0≤x≤1) NPs at working voltage of 8 V.
Co-reporter:Peiran Hu, Hongzhi Wang, Qinghong Zhang, and Yaogang Li
The Journal of Physical Chemistry C 2012 Volume 116(Issue 19) pp:10708-10713
Publication Date(Web):April 24, 2012
DOI:10.1021/jp3005647
A regular indium tin oxide (ITO) conductive network is fabricated by a simple “dipping and drying” process using cotton as a template. The flexible composite consists of an interconnected conductive network of ITO, which acts as a transport channel for charge carriers, and a poly(dimethyl siloxane) substrate. The composite shows a very high electrical conductivity of ∼5 S m–1, which is ∼12 times of magnitude higher than those of other ordinary ITO-based composites. Moreover, it exhibits superior electrical/mechanical performance when bent or twisted compared to other ITO-based composites. The unique network structure and outstanding electrical, mechanical, and optical properties of the composite possess great potential for use in flexible, foldable, and stretchable electronics and other devices.
Co-reporter:Yichuan Rui; Yaogang Li; Hongzhi Wang; Qinghong Zhang
Chemistry – An Asian Journal 2012 Volume 7( Issue 10) pp:2313-2320
Publication Date(Web):
DOI:10.1002/asia.201200590
Abstract
Anatase TiO2 nanorods with large specific surface areas and high crystallinity have been synthesized by surfactant-free hydrothermal treatment of water-soluble peroxotitanium acid (PTA). X-ray diffraction and TEM analysis showed that all TiO2 nanorods derived from PTA in different hydrothermal processes were in the anatase phase, and high aspect ratio TiO2 nanorods with chain-shaped structures were formed at 150 °C for 24 h by oriented growth. The nanorods were fabricated as photoanodes for high-efficiency dye-sensitized solar cells (DSSCs). DSSCs fabricated from the chain-shaped TiO2 nanorods gave a highest short-circuit current density of 14.8 mA cm−2 and a maximum energy conversion efficiency of 7.28 %, as a result of the presence of far fewer surface defects and grain boundaries than are present in commercial P25 TiO2 nanoparticles. Electrochemical impedance spectroscopy also confirmed that DSSCs based on the TiO2 nanorods have enhanced electron transport properties and a long electron lifetime.
Co-reporter:Sujun Yuan, Ruiyi Mao, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Electrochimica Acta 2012 60() pp: 347-353
Publication Date(Web):
DOI:10.1016/j.electacta.2011.11.069
Co-reporter:Ya Tang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Sensors and Actuators B: Chemical 2012 Volume 169() pp:229-234
Publication Date(Web):5 July 2012
DOI:10.1016/j.snb.2012.04.073
Co1−xNixFe2O4/multi-walled carbon nanotubes (MWCNTs) nanocomposites (x = 0.2, 0.4, 0.5, 0.6, 0.8) were synthesized via an in situ solvothermal method using ethylene glycol as solvent. X-ray diffraction analysis result confirmed that MWCNTs and high purity Co1−xNixFe2O4 nanocrystallites coexisted in the nanocomposites. Transmission electron microscopy revealed that 50–60 nm Co1−xNixFe2O4 nanoparticles (NPs) were densely clustered along the length of the MWCNTs. Substitution of the Co2+ by Ni2+ at octahedral sites was verified by vibrating sample magnetometry. Co1−xNixFe2O4/MWCNTs nanocomposites have a high selectivity for ammonia vapor, with a sensitivity greater than that observed for either bare MWCNTs or Co1−xNixFe2O4 NPs.
Co-reporter:Xiaoli Miao, Yaogang Li, Qinghong Zhang, Meifang Zhu, Hongzhi Wang
Materials Science and Engineering: C 2012 Volume 32(Issue 7) pp:2115-2121
Publication Date(Web):1 October 2012
DOI:10.1016/j.msec.2012.05.053
Commercial resin matrixes of dental composites generally utilize diluents such as triethylene glycol dimethacrylate (TEGDMA) to reduce viscosity. However, the diluents exhibited adverse effects such as higher volume shrinkage and diminished mechanical properties of the dental composites. To overcome these adverse effects, developing of both inorganic fillers and resin monomers is necessary to improve the properties of dental composite. In this work, monodispersed silica microspheres with a diameter of 400 nm were synthesized via the Stöber process. The as-prepared particles were silanized with 3-methacryloxypropyltrimethoxysilane (γ-MPS) and used as fillers. Additionally, ethoxylated bisphenol A dimethacrylate (EBPADMA) with lower viscosity and higher molecular mass was introduced as a base resin monomer, which could be used as resin matrixes with a low amount of diluent. Various resin mixtures of EBPADMA, bisphenol A diglycidyl dimethacrylate (Bis-GMA) and TEGDMA were prepared, which had a similar filler content (71 wt.%), and their mechanical properties, volume shrinkage, depth of cure and light transmission were examined. Among them, the resin mixture containing 70% EBPADMA and 30% TEGDMA exhibited the best compression strength (238.1 ± 5.4 MPa), depth of cure (4.02 ± 0.04 mm) and the lowest volume shrinkage (2.27%).Graphical abstractMonodispersive silica microspheres with a diameter of 400 nm were synthesized and used as fillers to develop a dental composite that has low volume shrinkage.Highlights► Monodispersed SiO2 microspheres with a diameter of 400 nm were synthesized and used as fillers. ► The resin composites using the SiO2 as fillers have a higher light transmission. ► The composite presented a volume shrinkage as low as 2.27% by tuning the resin composition.
Co-reporter:Shenyong Shi, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Progress in Natural Science: Materials International 2012 Volume 22(Issue 3) pp:224-230
Publication Date(Web):June 2012
DOI:10.1016/j.pnsc.2012.04.009
The 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) powder had three particle size distributions, while the fine one was lower than 100 nm. The 3Y-TZP compact was prepared by dry-pressing under pressures ranged from 10 to 30 MPa and then presintered at 1250 °C for 2 h. The matrix dry-pressed under the pressure of 20 MPa had a porosity of 16.7% and could be easily processed by computer aided design and computer aided manufacturing (CAD/CAM), and which had been infiltrated by the La2O3–Al2O3–SiO2 glass at 1200 °C for 4 h. The flexural strength and fracture toughness of the composite were 710.7 MPa and 6.51 MPa m1/2, respectively. The low shrinkage (0.3%) of the composite can satisfy the net-shape fabrication standard. XRD results illustrated that zirconia in the La2O3–Al2O3–SiO2 glass-infiltrated 3Y-TZP all-ceramic composite was mainly in the tetragonal phase. SEM and EDS results indicated that the pores of the matrix were almost filled by the La2O3–Al2O3–SiO2 glass.
Co-reporter:Pengtao Shao, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 44) pp:17972-17977
Publication Date(Web):13 Oct 2011
DOI:10.1039/C1JM12128F
Mn-doped ZnSe nanocrystals (Mn:ZnSe d-dots) that emit white light were synthesized in aqueous media in microfluidic reactors. White light emission from Mn:ZnSe d-dots was a result of combined emission of blue light (emission from non-coordinated surface selenium sites) and yellow light (4T1 → 6A1 emission from Mn2+ ions). Emission from non-coordinated surface selenium sites was realized by adjusting the ratio of the flow volumes of [Zn]/[Mn] and the mass of stabilizer added. Photoluminescence from the Mn:ZnSe d-dots was easily tuned from 580 to 602 nm by regulating flow volume. Under the optimal experimental conditions, Mn:ZnSe d-dots that emit white light with a quantum yield of about 10.2% were fabricated.
Co-reporter:Yunxin Gu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 44) pp:17790-17797
Publication Date(Web):11 Oct 2011
DOI:10.1039/C1JM13351A
Oxynitride phosphor mat consisting of CaSi2O2N2:Eu nanofibers is prepared by electrospinning the fiber precursor and subsequent nitridation. As-prepared fiber precursor is smooth and uniform with a diameter of 400–600 nm. After removing organic templates and nitridation, the fiber morphology is well retained and a smooth phosphor mat consisting of uniform fiber network is obtained. X-Ray diffraction results confirm that a pure CaSi2O2N2 phase can be obtained at low temperature of around 1300 °C. Series of experiments simulating the LED working environment are conducted and the results confirm that the CaSi2O2N2:Eu nanofiber mat can keep high transmittance and strong emission intensity at the same time, which can be attributed to the uniform fiber arrangement in the nanostructure. Moreover, a new LED packaging process is attempted by using CaSi2O2N2:Eu nanofiber mat. Different colour temperatures can be obtained by employing phosphor mats with different thicknesses. Phosphor agglomeration in the conventional packaging process is avoided, and the efficacy and light homogeneity of the lamp are significantly improved.
Co-reporter:Chengyi Hou, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 28) pp:10512-10517
Publication Date(Web):09 Jun 2011
DOI:10.1039/C1JM11086A
Aqueous-dispersed graphene/Fe3O4 hybrids are prepared using a two-step method. Functional microgels composed of the poly(N-isopropylacrylamide) (PNIPAAm) and the as-prepared graphene/Fe3O4 hybrids are synthesized in a microfluidic reactor for the first time. The microgel exhibits a good response to an external magnet and near-infrared (NIR) laser irradiation, indicating that it could be used as a light-driven and magnetic controlled switch for applications in microreactors.
Co-reporter:Pengtao Shao, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2011 vol. 21(Issue 1) pp:151-156
Publication Date(Web):22 Oct 2010
DOI:10.1039/C0JM01878C
The aqueous synthesis of color-tunable and stable Mn2+-doped ZnSe quantum dots (Mn:ZnSe d-dots) via a nucleation-doping strategy was realized in a three-necked flask and the photoluminescence (PL) peak position was easily tuned from 572 nm to 602 nm by prolonging the epitaxial-growthg time. The chemical stability of the resulting d-dots is much better than that of CdTevia an aqueous synthesis. Separation of nucleation and growth of crystallization, and multiple-step-injection of both zinc precursor and 3-mercaptopropionic acid (MPA) stabilizing reagent, were employed to realize a balanced, mutually diffused interface and a pure ZnSe shell. The resulting nanocrystals show excellent optical properties, implying that nanocrystals with high quality could also be achieved via aqueous synthesis.
Co-reporter:Zhifu Liu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Chemical Communications 2011 vol. 47(Issue 48) pp:12801-12803
Publication Date(Web):31 Oct 2011
DOI:10.1039/C1CC15588A
Structural colored fiber was fabricated by an isothermal heating evaporation-induced self-assembly method. Under ambient white light illumination, the fibers appear colored due to optical reflectance, which is determined by the lattice constants of the photonic crystals. By controlling the size and layers of the silica nanospheres, the fiber color can be changed.
Co-reporter:Chengyi Hou, Qinghong Zhang, Meifang Zhu, Yaogang Li, Hongzhi Wang
Carbon 2011 Volume 49(Issue 1) pp:47-53
Publication Date(Web):January 2011
DOI:10.1016/j.carbon.2010.08.040
Graphene/Fe3O4 hybrids were prepared using a one-step solvothermal method in ethylene glycol using graphite oxide as the graphene precursor and FeCl3·6H2O as the Fe3O4 precursor. The Fe3O4 nanoparticles, with a diameter of 100–200 nm, were densely and randomly deposited on the graphene sheets. The electrical conductivity of the hybrid reached 1.011 × 102 S m−1 and the saturation magnetization reached 83.6 emu g−1. The as-prepared magnetically-functionalized graphene hybrid was used for the functionalization of hydrogels for the first time.
Co-reporter:Zhongyuan He, Zhenhua Chen, Yaogang Li, Qinghong Zhang and Hongzhi Wang
CrystEngComm 2011 vol. 13(Issue 7) pp:2557-2565
Publication Date(Web):10 Feb 2011
DOI:10.1039/C0CE00289E
In this work, different morphologies of In2O3 products were fabricated by the calcination of In(OH)3, which was synthesized through a hydrothermal route, with tuning of the molar ratio of indium to urea. The In2O3 inherited the morphology of its precursor and the proposed formation mechanisms for the In(OH)3 structures, assisted by the molar ratio of indium to urea, were put forward. The formation mechanism of In(OH)3 cubes at a higher molar ratio of In to urea was ascribed to Ostwald ripening mechanism, while the growth of In(OH)3 nanorod-based flowers at a lower molar ratio of In to urea was attributed to the oriented attachment of In(OH)3 nanoparticles coordinated with the complexation of In3+ to urea, in which the urea may play ternary roles including being the alkaline media, the coordinating agent and the surface anchored organic molecules.
Co-reporter:Yunxin Gu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2011 Volume 509(Issue 6) pp:L109-L112
Publication Date(Web):10 February 2011
DOI:10.1016/j.jallcom.2010.11.158
Tunable color point and efficient excitation are two important challenges for improving white light LEDs. In this paper, red-shift in the emission spectra of Sr2SiO4:Eu has been achieved, and the excitation band has been tuned to fit the blue LED chips simultaneously by doping N into the host. XRD results showed that the unit cell volume markedly increased after nitridation. Moreover, nitridation resulted in the increase in weight loss, which can be attributed to the substitute of Si–O bonds by Si–N bonds. The effect of nitridation on the luminescence properties was well discussed.
Co-reporter:Difeng Qian, Yaogang Li, Qinghong Zhang, Guoying Shi, Hongzhi Wang
Journal of Alloys and Compounds 2011 Volume 509(Issue 41) pp:10121-10126
Publication Date(Web):13 October 2011
DOI:10.1016/j.jallcom.2011.08.055
Transparent and surfactant-free TiO2 sols containing anatase nanocrystals were prepared by the hydrothermal treatment of water-soluble peroxotitanium acid (PTA) at a temperature of 120 °C. The TiO2 nanocrystals were characterized by transmission electron microscopy (TEM). The TEM results indicated that the TiO2 nanocrystals were nanorod-like with diameters of less than 7 nm after the subsequently hydrothermal treatment. A gradient layer between the transparent fluorine doped SnO2 (FTO) layer and the porous titanium dioxide nanocrystalline film for dye-sensitized solar cells (DSSCs) photoelectrodes, was made with the as-prepared TiO2 sols. The TiO2 gradient layers were characterized by field-emission scanning electron microscopy and UV–vis absorption spectrometry. After the gradient layer deposition on the FTO coated glass, the composite multilayer film exhibited the visible light transmittance of 80% which approached to that of bare FTO glass. The photo-to-electric energy conversion efficiency of the N719 dye-sensitized solar cell had significantly improved from 4.2% to 5.6% in the presence of the compact layer between FTO and the porous TiO2 nanocrystalline film under of AM1.5 illumination (100 mW/cm2). The remarkable improvements in short-circuit current for the DSSCs was due to the effective gradient layer at the FTO–TiO2 interface which prevented direct contact of electrolytes with FTO and consequently reduced charge recombination losses.Graphical abstractDye-sensitized solar cells with TiO2 nanocrystalline porous film in absence of compact film (A) and in presence of compact film in thickness of 1.0 μm (B), 2.5 μm (C), 4.0 μm (D), respectively.Highlights► Anatase TiO2 sols were prepared by the hydrothermal treatment of peroxotitanium acid. ► TiO2 sols were used for DSSC photoelectrode as the compact film on FTO layer. ► The transmittance of the TiO2 compact film on FTO reached 80%. ► The η of DSSCs in the presence of the compact film has improved significantly from 4.2% to 5.6%.
Co-reporter:Ying Chen, Xinwei Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2011 Volume 509(Issue 9) pp:4053-4059
Publication Date(Web):3 March 2011
DOI:10.1016/j.jallcom.2011.01.018
A novel magnetic nanocomposite of multiwalled carbon nanotubes (MWCNTs) decorated with Co1−xZnxFe2O4 nanocrystals was synthesized successfully by an effective solvothermal method. The as-prepared MWCNTs/Co1−xZnxFe2O4 magnetic nanocomposite was used for the functionalization of P/H hydrogels as a prototype of device to show the potential application of the nanocomposites. The nanocomposites were characterized by X-ray diffraction analysis, transmission electron microscopy and vibrating sample magnetometer. The results show that the saturation magnetization of the MWCNTs/Co1−xZnxFe2O4 magnetic nanocomposites increases with x when the Zn2+ content is less than 0.5, but decreases rapidly when the Zn2+ content is more than 0.5. The saturation magnetization as a function of Zn2+ substitution reaches a maximum value of 57.5 emu g−1 for x = 0.5. The probable synthesis mechanism of these nanocomposites was described based on the experimental results.Research highlights▶ MWCNTs/Co1−xZnxFe2O4 magnetic nanocomposites were synthesized via a one-step solvothermal approach. And the MWCNTs/Co1−xZnxFe2O4 magnetic nanocomposite functionalized PNIPAAm gels were prepared and expected to be used as a light-driven and magnetic controlled switch in microreactors. Results indicated that cobalt, zinc and iron cations added to the solution were compactly attached by electrostatic attraction on the surface of pretreated MWCNTs, and Co1−xZnxFe2O4 nanocrystallites were formed gradually. The saturation magnetization of the magnetic nanocomposites reached a maximum value of 57.5 emu g−1 for x = 0.5. Furthermore, these nanocomposites display a high magnetic sensitivity and have a high saturation magnetization. And the PNIPAAm/MWCNTs/Co1−xZnxFe2O4 hydrogels had been prepared as a prototype of device to show the potential application of the nanocomposites for the first time. We believe it will be of interest to the journal's readers, especially in the fields of the technology of magnetic composites.
Co-reporter:Cheng Bi, Meifang Zhu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Materials Chemistry and Physics 2011 Volume 126(Issue 3) pp:596-601
Publication Date(Web):15 April 2011
DOI:10.1016/j.matchemphys.2011.01.015
Ba1−xLaxTiO3/multi-walled carbon nanotube (MWCNT) nanocomposites with different concentrations of La3+ doping, were synthesized by a solvothermal process. The prepared nanocomposites had a hybrid microstructure in which Ba1−xLaxTiO3 nanocrystals with diameter of 10–30 nm were firmly immobilized on the MWCNTs sidewalls. Electromagnetic (EM) wave absorption properties of La-doped BaTiO3/MWCNT nanocomposites were investigated in the 7.5–18 GHz frequency range for an absorber thickness of 1 mm. The reflection loss (RL) calculated from the EM parameters of the samples, moved to low frequencies with increasing La3+ doping. The widest absorption bandwidth, with the lowest frequency range, was observed in a nanocomposite doped with 1.5 at% La3+. An RL exceeding −5 dB for this sample was obtained in the frequencies ranging from 9.6 to 16.3 GHz, with the optimal RL of −17.4 dB at 10.9 GHz, due to enhanced interfacial polarization resulting in developed ε″rε″r. In addition, the RL for the sample shifted to the low frequency region and the peaks became sharper in the 2–18 GHz frequency range with increasing absorber thickness. For BaTiO3/MWCNT nanocomposites, La3+ doping can greatly improve the EM wave absorbing ability in a thin absorber thickness and the donor-doped nanocomposites show promise for application in EM wave shielding materials with broad absorption bandwidths.Research highlights► A kind of Ba1−xLaxTiO3/multi-walled carbon nanotube electromagnetic wave (EM) absorption material was synthesized. ► The influence of absorber thickness and different concentrations of La3+ doping was investigated. ► The sample doped with 1.5 at% La3+ shows the best EM absorption property. ► Increases in both La3+ doping and absorber thickness cause frequency region to move to a lower frequency.
Co-reporter:Qinghui Mu, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Sensors and Actuators B: Chemical 2011 Volume 155(Issue 2) pp:804-809
Publication Date(Web):20 July 2011
DOI:10.1016/j.snb.2011.01.051
Large arrays of one-dimensional uniform-sized TiO2 nanofibers (TNFs) were prepared through a template-free method, and used as a working electrode in a transparent microfluidic device made from poly (dimethyl siloxane) (PDMS) to perform efficient photoelectrocatalysis for rapid and undefiled determination of chemical oxygen demand (COD). Photoelectrochemical measurements were used to evaluate the response of TNFs to the intensity of exciting light and the applied potential bias. The photoelectrocatalysis of TNFs in PDMS-based microfluidic device exhibited excellent performance for determination of COD. The practical limit of determination of 0.95 mg/L COD with a working range of 0–250 mg/L was achieved. The relative standard deviation (RSD) was 1.85% for 10 repeated measurements of 0.3 mmol/L glucose with COD value of 57.6 mg/L.
Co-reporter:Zhongyuan He;Qinghong Zhang;Yaogang Li
Biomedical Microdevices 2011 Volume 13( Issue 5) pp:
Publication Date(Web):2011 October
DOI:10.1007/s10544-011-9556-0
A capillary microchannel (CM) containing TiO2-coated ZnO nanorod arrays was applied as a novel microfluidic device to selectively bind and enrich phosphopeptides. The device was prepared by pumping a TiO2 sol into a CM containing preformed ZnO nanorod arrays. Different thicknesses of the TiO2 coating were obtained by controlling the flow duration of TiO2 sol. The modified CM achieved uninterrupted high-throughput introduction, capture and enrichment of phosphopeptides using continuous-flow operation. The microfluidic device based on the modified CM showed great selectivity, sensitivity and durability for the enrichment of phosphopeptides from tryptic protein digests. These results suggest that microfluidic chips employing this strategy can be used for rapid and high-throughput enrichment of phosphopeptides from complex mixtures.
Co-reporter:Hua Wang, Meifang Zhu, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Materials Science and Engineering: C 2011 Volume 31(Issue 3) pp:600-605
Publication Date(Web):8 April 2011
DOI:10.1016/j.msec.2010.11.023
The aim of this study was to investigate the mechanical property effects of co-filling dental resin composites with porous diatomite and nanosized silica particles (OX-50). The purification of raw diatomite by acid-leaching was conducted in a hot 5 M HCl solution at 80 °C for 12 h. Both diatomite and nanosized SiO2 were silanized with 3-methacryloxypropyltrimethoxysilane. The silanized inorganic particles were mixed into a dimethacrylate resin. Purified diatomite was characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy and an N2 adsorption–desorption isotherm. Silanized inorganic particles were characterized using Fourier transform infrared spectroscopy and a thermogravimetric analysis. The mechanical properties of the composites were tested by three-point bending, compression and Vicker's microhardness. Scanning electron microscopy was used to show the cross-section morphologies of the composites. Silanization of diatomite and nanosized silica positively reinforced interactions between the resin matrix and the inorganic particles. The mechanical properties of the resin composites gradually increased with the addition of modified diatomite (m-diatomite). The fracture surfaces of the composites exhibited large fracture steps with the addition of m-diatomite. However, when the mass fraction of m-diatomite was greater than 21 wt.% with respect to modified nanosized silica (mOX-50) and constituted 70% of the resin composite by weight, the mechanical properties of the resin composites started to decline. Thus, the porous structure of diatomite appears to be a crucial factor to improve mechanical properties of resin composites.
Co-reporter:Yunxin Gu, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 29) pp:6050-6056
Publication Date(Web):16 Jun 2010
DOI:10.1039/C0JM00118J
Rod-like, uniform, and poorly aggregated BaSi2O2N2:Eu powders with tunable luminescence for white LEDs have been successfully synthesized by direct gas-reduction nitridation from the core-shell oxide (Ba,Eu)CO3@SiO2. Maximization of the contact surface between the reactants and minimization of diffusion distances improved the efficiency of the nitridation. Thus, the desired oxynitride phosphors were obtained at relatively low temperatures (around 1100–1200 °C). Under these conditions, the (Ba,Eu)CO3 cores melted into small seeds which decreased the particle size and promoted the oriented growth of BaSi2O2N2:Eu. The nucleation and subsequent crystal growth in (Ba,Eu)CO3@SiO2 were further discussed in the samples with different Ba/Si ratios. By controlling the nitridation process, tunable luminescence was achieved in the range of 490–530 nm. The low sedimentation rate of the phosphors from this route shows additional advantages in the LED packaging.
Co-reporter:Xiaoxu Zhu, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 9) pp:1766-1771
Publication Date(Web):14 Jan 2010
DOI:10.1039/B922873J
A microfluidic reactor heated by microwave (MW) irradiation was utilized for the first time to prepare LaF3/LaPO4:Ce,Tb nanocrystals (NCs) using ethylene glycol (EG) as solvent. Redispersible and water-soluble LaF3 nanoparticles with a mean diameter of 4.5 nm, and LaPO4 nanorods with a length of 60–70 nm and diameter of 10–15 nm were simply obtained. Dielectric heating by the irradiation and the special MW effect combined with the microfluidic reactor accelerate the nucleation stage and promote the growth stage of NCs, which results in improved luminescent properties and yields of products.
Co-reporter:Zhuang Sun, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2010 Volume 506(Issue 1) pp:338-342
Publication Date(Web):10 September 2010
DOI:10.1016/j.jallcom.2010.06.203
High concentration Eu3+ doped La2Ti2O7 phosphor with good crystallinity was prepared via solid-state method. This phosphor can emit intense red light with a peak around 612 nm corresponding to the 5D0 → 7F2 transitions of Eu3+. The luminescent intensity excited at 465 nm, which corresponds to the wavelength of InGaN-based LEDs, is comparable with the intensity excited at 396 nm. The emission intensity increased with increasing Eu3+ concentration up to 30 mol%, and then decreased due to the concentration quenching. The White LED (WLED) fabricated by coating a mixture of Y3Al5O12:Ce3+ and La2Ti2O7:Eu3+ onto a blue InGaN chip showed higher color rendering index than the WLED fabricated by coating Y3Al5O12:Ce3+(Y3Al5O12:Ce3+-WLED). This phosphor also has excellent thermal stability, and the luminous intensity can remain 75.46% when it was heated to 200°. By optimizing the Eu3+ concentration and calcination temperature, we demonstrated that La2Ti2O7:Eu3+ was a promising red phosphor under blue light (465 nm) for high-power commercial Y3Al5O12:Ce3+-WLEDs.Research highlightsLa2Ti2O7:Eu3+phosphors were synthesized by a solid state reaction method, which have good thermal stability and strong luminescent intensity. Because this phosphor was efficiently excited by 465 nm, it can well match the blue LED Chips. The WLED fabricated by coating a mixture of Y3Al5O12:Ce3+ and La2Ti2O7:Eu3+ onto blue InGaN chip showed higher color rendering index than the Y3Al5O12:Ce3+-WLED and its good thermal stability can meet the demand of high-power LEDs.
Co-reporter:Jiapeng Fu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Luminescence 2010 Volume 130(Issue 2) pp:231-235
Publication Date(Web):February 2010
DOI:10.1016/j.jlumin.2009.08.012
The Eu-doped CaTiO3 particles with a good crystallinity were prepared via sol–gel method. The phosphors showed a strong red emission corresponding to 5D0→7F2 (618 nm) of Eu3+ under the near-ultraviolet excitation (400 nm). X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), photoluminescent (PL) analysis and Brunauer–Emmett–Teller (BET) specific surface area measurement were utilized to characterize the CaTiO3:Eu3+ particles. The concentration quenching and thermal quenching of the samples were discussed as well. The optimal concentration and the calcination temperature were 16 mol% of Eu3+ and 1400 °C for these phosphors, and the possible reason was discussed as well. CaTiO3:Eu3+ is a promising red phosphor under near-ultraviolet excitation for various applications.
Co-reporter:Chengyi Hou, Hao Yu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2010 Volume 491(1–2) pp:431-435
Publication Date(Web):18 February 2010
DOI:10.1016/j.jallcom.2009.10.217
Monodisperse Co–Zn ferrite (Co1−xZnxFe2O4) nanospheres have been synthesized by the solvothermal method. In this process, glycol was used as a solvent, anhydrous sodium acetate was used as an alkalinity additive and polyethylene glycol 200 was used as a surfactant. The as-prepared samples were characterized in detail by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). Results showed that a large number of high purity Co1−xZnxFe2O4 nanocrystallites were synthesized and these nanocrystallites underwent oriented aggregation to form nanospheres. The variation of saturation magnetization (Ms) value of the samples was studied. The maximum saturation magnetization value of the as-prepared sample (Co0.5Zn0.5Fe2O4) reached 64.6 emu g−1.
Co-reporter:Bingjie Zhu, Meifang Zhu, Qinghong Zhang, Liyun Cheng, Yaogang Li, Hongzhi Wang
Synthetic Metals 2010 Volume 160(19–20) pp:2151-2154
Publication Date(Web):October 2010
DOI:10.1016/j.synthmet.2010.07.045
Conducting composites core layers of indium tin oxide (ITO) particles embedded in polypyrrole (PPy) were prepared by polymerization. The morphology, molecular structure and electrical property of the composites were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscope, thermogravimetric analysis and conductivity measurement methods. The results indicated the ITO combined with PPy by chemical bond energy not the physical combine. Electrical conductivity measurements on the samples pressed into pellets showed that the maximum conductivity attained 13.97 ± 0.05 S/cm for PPy/ITO composites, at ITO particle doping concentration of 50 wt%. The highest conductivity of PPy/ITO crossing-rod composites was 11.00 ± 0.05 S/cm, of which the content of ITO crossing-rod was 15 wt%. The PPy/ITO composites showed a higher conductivity by comparing with that of neat PPy.
Co-reporter:Zhongyuan He, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Materials Chemistry and Physics 2010 Volume 119(1–2) pp:222-229
Publication Date(Web):15 January 2010
DOI:10.1016/j.matchemphys.2009.08.056
A novel route to pattern microchannels of microfluidics devices utilizing ZnO micro/nanostructures was demonstrated. Firstly well-dispersed ZnO crystals were seeded on the inner walls of long silica microcapillaries through utilization of nanosized reverse micelles combining with an unconventional demulsification technique. Based on the as-prepared ZnO seeds, the flower-like clusters of ZnO nanorod arrays with controllable distribution density were obtained on the inner surface of the microcapillaries. By changing the molar ratio of water to cetyltrimethyl ammonium bromide and the concentration of reactants in the reverse micelles, distances among the seeds were well controlled which resulted in the controllable distribution density of the final ZnO nanorod arrays. We used the microcapillaries with ZnO nanorods as microreactors to photocatalyze methylene blue degradation. The photocatalytic property of the microreactors was influenced by the distribution density of the nanorods and the residence time in the microchannel. The results here present a new possibility for the formation of nanopatterns on surface of long microchannels. Moreover, further improvements of this approach are expected to result in unique architectures at the nanoscale in microchannels which is important for the development of functional integrated microfluidic devices.
Co-reporter:Wei Yan, Wan Jiang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Materials Science and Engineering: B 2010 Volume 171(1–3) pp:144-148
Publication Date(Web):25 July 2010
DOI:10.1016/j.mseb.2010.03.088
Monodisperse Ni–Zn ferrites (NixZn1−xFe2O4) microspheres have been synthesized via solvothermal method. X-ray diffraction pattern (XRD), transmission electron microscope (TEM), field emission-scanning electron microscopy (FE-SEM) and vibrating sample magnetometry are used to characterize the shape, structure, size and magnetic properties of the as-synthesized magnetic microspheres. The powder XRD patterns revealed the formation of the single phase spinel structure for the synthesized materials. TEM and FE-SEM show the size and morphology of the as-synthesized sample in detail. The maximum magnetic saturation value of the Ni0.2Zn0.8Fe2O4 microspheres can reach 60.6 emu g−1. These magnetic NixZn1−xFe2O4 microspheres are expected to have wide applications in bionanoscience and electronic devices technology.
Co-reporter:Liping Zhu;Yaogang Li;Qinghong Zhang
Biomedical Microdevices 2010 Volume 12( Issue 1) pp:169-177
Publication Date(Web):2010 February
DOI:10.1007/s10544-009-9373-x
We report a novel and facile method for fabricating coaxial microfluidic devices processing various dimensions at low cost, in which polypropylene hollow fibers or glass capillaries are used as the tip of the dispersed phase injection tube. With this coaxial microfluidic device, monodisperse biocompatible microspheres ranging from 300 to 800 μm were obtained by collecting oil-in-water or water-in-oil emulsions and solidifying the suspended microspheres. Microsphere size could be controlled by changing the tips or tuning the concentrations of the dispersed and continuous phases. By adding functional nanoparticles into the dispersed phase, it was demonstrated that fluorescent and magnetic microspheres can be fabricated easily using these microfluidic devices.
Co-reporter:Yun Zhi, Yaogang Li, Qinghong Zhang, and Hongzhi Wang
Langmuir 2010 Volume 26(Issue 19) pp:15546-15553
Publication Date(Web):September 8, 2010
DOI:10.1021/la1019313
Flaky layered double hydroxides (FLDH) composed of cross-linked nanoflakes were prepared by the reconstruction of their oxides in alkali solution. The effect of reconstruction temperatures on the physicochemical properties was investigated. FLDH with a specific surface area of as high as 217 m2/g was obtained at a reconstruction temperature of 6 °C, and its derived flaky mixed metal oxides (FMMO) had a specific surface area of 249 m2/g. The ZnO nanoparticles were homogeneously deposited on the surface of the FLDH by coprecipitation. After calcination at 500 °C for 2 h, the ZnO-coated FLDH was transformed into ZnO-coated flaky mixed metal oxides (FMMO). The powders were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscope, N2 adsorption−desorption isotherm, UV-vis diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. In the presence of FLDH as a support, the ZnO nanoparticles were of about 10 nm in size and showed higher photocatalytic decomposition of acid red G than bare ZnO powder prepared under similar experimental conditions. It should be noted that the ZnO-coated FMMO combined excellent adsorption with photocatalytic activity. The flaky structure of mixed metal oxides appears to play important roles in the adsorption and photodecomposition process.
Co-reporter:Peifeng Liu;Zonghai Li;Mingjie Zhu
Journal of Materials Science: Materials in Medicine 2010 Volume 21( Issue 2) pp:551-556
Publication Date(Web):2010 February
DOI:10.1007/s10856-009-3925-8
This study aims to determine the sensitivity, specificity and accuracy of epidermal growth factor receptor monoclonal antibody (EGFRmAb) modified poly(lactic acid-co-l-lysine) nanoparticles (PLA-PLL-EGFRmAb) NPs delivery system to EGFR positive cancer cells. In the study, a new PLA-PLL-EGFRmAb NPs was prepared. The cellular cytotoxicity, cellular uptake, and the targeted effect for hepatocellular carcinoma of PLA-PLL-EGFRmAb NPs were investigated. In vitro, the findings of Flow cytometry and Confocal Laser scanning Biological Microscopy showed that PLA-PLL-EGFRmAb NPs can bind to hepatocellular carcinoma cells and were uptaken effectively. In vivo in the SMMC-7721 xenograft mouse model, PLA-PLL-EGFRmAb NPs could target to the tumor effectively, which demonstrated a better targeting. These results showed that the PLA-PLL-EGFRmAb NPs have the potential to be used as a target delivery carrier for tumor therapies.
Co-reporter:Qi Zhang, Meifang Zhu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Composites Science and Technology 2009 Volume 69(Issue 5) pp:633-638
Publication Date(Web):April 2009
DOI:10.1016/j.compscitech.2008.12.011
Linear polyethyleneimine (PEI) was used as a non-covalent functionalizing agent to modify multi-walled carbon nanotubes (MWCNTs). Fe3O4 nanoparticles were then formed along the sidewalls of the as-modified MWCNTs through a simple solvothermal method. X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, and vibrating sample magnetometry were used to characterize the MWCNT/Fe3O4 nanocomposites. Results indicated that Fe3O4 nanoparticles with diameters ranging from 50 to 200 nm were attached to the surface of the MWCNTs by electrostatic interaction. PEI was found to improve the electrical conductivity of the MWCNT/Fe3O4 nanocomposites. The magnetic saturation value of these magnetic nanocomposites was 61.8 emu g−1. These magnetic MWCNT/Fe3O4 nanocomposites are expected to have wide applications in bionanoscience and technology.
Co-reporter:Jiapeng Fu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds 2009 Volume 485(1–2) pp:418-421
Publication Date(Web):19 October 2009
DOI:10.1016/j.jallcom.2009.05.128
A highly Eu3+-doped, highly crystalline CaTiO3 phosphor was prepared via a solid-state (SS) method, and its structure was confirmed by X-ray diffraction (XRD). Photoluminescence (PL) data showed that this phosphor was efficiently excited by near-ultraviolet (NUV) light at wavelength around 400 nm and emitted intense red light with a broad peak around 618 nm corresponding to the 5D0 → 7F2 transition of Eu3+. The relative emission intensity increased with increasing Eu3+ concentration up to 28 mol%, which is extremely high in this field, then decreased due to concentration quenching. The concentration quenching and thermal quenching of the samples are discussed. By optimizing the calcination temperature and Eu3+ concentration, it was shown that CaTiO3:Eu3+ is a promising red phosphor under near ultraviolet excitation for various applications.
Co-reporter:Shuang Li;Yaogang Li;Wugang Fan;Qinghong Zhang
European Journal of Inorganic Chemistry 2009 Volume 2009( Issue 27) pp:4078-4084
Publication Date(Web):
DOI:10.1002/ejic.200900371
Abstract
The transparent TiO2 sol contained of anatase crystallites was prepared by peptization of anatase TiO2 precipitates. With the hydrothermal treatment of TiO2 sol at 150 °C, the dispersible and nanorod-like TiO2 nanocrystals were formed by an oriented attachment mechanism. After further hydrothermal treatment of the mixture of nanorod-like TiO2 nanocrystals and the original sol, branched and nanoring-like nanostructures in the anatase phase were obtained. The as-prepared TiO2 nanocrystals were characterized by X-ray diffraction, FT-Raman spectrometry, UV/Vis absorption spectrometry, and transmission electron microscopy (TEM). TEM results indicated that TiO2 nanocrystals were nanorod-like, and more complex microstructures such as the ring-like and branched TiO2 nanostructures with diameters less than 10 nm were formed especially in the two-step hydrothermal treatment. The adsorption of ruthenium dye (N719) over the nanocrystals with different microstructures was investigated. The adsorption results showed the nanorod-like anatase TiO2 nanocrystals had a high capacity for the ruthenium dye adsorption. The powders were used as electrodes of dye-sensitized solar cells and showed a conversion efficiency of 5.75 % under 1 sun illumination unit of simulated sunlight. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Co-reporter:Yunxin Gu, Qinghong Zhang, Yaogang Li, Hongzhi Wang, Rong-Jun Xie
Materials Letters 2009 Volume 63(Issue 16) pp:1448-1450
Publication Date(Web):30 June 2009
DOI:10.1016/j.matlet.2009.03.045
Yttrium doped CaSi2O2N2:Eu2+ phosphors were prepared by the solid state reaction method. Large increases in the emission have been achieved by adding Y3+ ions in the host. XRD data revealed that the lattice expanded as doping Y3+ ions. XPS results suggested that there were more Eu2+ ions incorporated into the lattice of Y3+ doped samples than that of undoped samples. The doping effect of Y3+ ions has been discussed systematically. By using this novel Y3+ doped CaSi2O2N2:Eu2+ phosphor, bright daylight emission with luminous efficiency (ηL) of 44 lm/W, color rendering index (CRI) of 82 and correlated color temperature (CCT) of 5300 K can be generated from white LED.
Co-reporter:Qi Zhang, Meifang Zhu, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Materials Chemistry and Physics 2009 Volume 116(2–3) pp:658-662
Publication Date(Web):15 August 2009
DOI:10.1016/j.matchemphys.2009.05.029
Mn1−xZnxFe2O4 nanospheres were self-assembled alongside the multi-walled carbon nanotubes (MWCNTs) via solvothermal method. The shape, structure, and size of the as-synthesized sample were characterized by X-ray diffraction pattern (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results shown that a large number of the high purity Mn1−xZnxFe2O4 nanocrystallites were decorated on the sidewalls of the MWCNTs, and these nanocrystallites aggregated around the MWCNTs templates formed spherical aggregation. The maximum magnetic saturation value of the Mn1−xZnxFe2O4/MWCNTs nanocomposites reached 55.6 emu g−1. The probable formation mechanism of the nanocomposites was also investigated based on the experimental results.
Co-reporter:Sujun Yuan, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 348(1–3) pp:76-81
Publication Date(Web):20 September 2009
DOI:10.1016/j.colsurfa.2009.06.040
The nanocomposites of magnesium–aluminium–carbonate–layered double hydroxides (Mg–Al–CO3–LDHs) and ZnO nanorods were prepared via a homogeneous precipitation process. The presence of ZnO nanorods made the calcined Mg–Al–CO3–LDHs, the strong adsorptive adsorbents for anions, have a photocatalytic activity. Both Mg–Al–CO3–LDHs and the nanocomposites with various ZnO/Mg–Al–CO3–LDHs mass ratios from 0.5:1 to 3:1 were characterized by X-ray diffraction, transmission electron microscope and UV–vis diffuse reflectance spectra. The nanocomposites quickly adsorbed the anionic dyes such as acid red G (ARG) without the light illumination, and the adsorbed dyes on the recovered nanocomposites were then degraded in a separated photocatalytic reactor. The adsorption ability of the nanocomposites and their photocatalytic activities for the removal of ARG were evaluated by the Fourier transform infrared spectra and UV–vis extinction spectra. The sample at 3:1 ZnO/Mg–Al–CO3–LDHs mass ratio was shown to have higher photocatalytic efficiencies.
Co-reporter:Sujun Yuan;Yaogang Li;Qinghong Zhang
Research on Chemical Intermediates 2009 Volume 35( Issue 6-7) pp:
Publication Date(Web):2009 September
DOI:10.1007/s11164-009-0094-9
Nanocomposites of magnesium aluminium layered double hydroxides with carbonate anions (Mg–Al–CO3-LDHs) and ZnO nanorods were prepared by a homogeneous precipitation process. The ZnO nanorods give the calcined Mg–Al–CO3-LDHs, strong adsorbents of anionic dyes, photocatalytic activity. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the nanocomposites was investigated by degradation of acid red G in aqueous solution, and the nanocomposite with the ZnO-to-Mg–Al–CO3-LDHs mass ratio of 1:1 had the highest photocatalytic activity in this photocatalytic reaction.
Co-reporter:Qi Zhang, Meifang Zhu, Qinghong Zhang, Yaogang Li and Hongzhi Wang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 35) pp:15538-15543
Publication Date(Web):August 7, 2009
DOI:10.1021/jp9036606
Nanocrystals of two indium tin oxide (ITO) polymorphs (rhombohedral and cubic) were deposited on the sidewalls of the multiwalled carbon nanotubes (MWCNTs) by a simple coprecipitation process. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM) images, select area electron diffraction patterns (SAED), and energy-dispersive X-ray (EDX) spectroscopy were used to characterize the as-prepared samples. The results indicated that tuning of the ITO phase in the nanocomposites can be selectively achieved via controlling the pH value of the coprecipitation process and the temperature of the subsequent calcination. The formation mechanism of the ITO/MWCNT nanocomposites was also investigated. Electrical conductivity measurements on the samples pressed into pellets showed that the maximum conductivities attained were 0.52 ± 0.05 and 0.65 ± 0.04 S·cm−1 for the rhombohedral and cubic ITO/MWCNT nanocomposites, respectively, at a dopant concentration of 12.5 wt %. The electrical conductivity of the nanocomposites was significantly enhanced compared to the pristine MWCNTs.
Co-reporter:Huashun Zhang, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Materials Letters 2008 Volume 62(17–18) pp:2729-2732
Publication Date(Web):30 June 2008
DOI:10.1016/j.matlet.2008.01.025
Nanocrystalline LaTiO2N with a surface area of 27.5 m2/g was synthesized by nitridation of amorphous La2O3/TiO2 composite powder at 900 °C for 8 h using NH3 as the reactant gas. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) results revealed that the as-prepared LaTiO2N nanocrystals had a mean diameter of about 30 nm. It was found that the absorption edge of the oxynitride is significantly red-shifted compared with that of La2Ti2O7 as increasing the nitridation temperature. The UV–vis absorption spectra indicated that the synthesized oxynitrides displayed good light absorption properties not only in the ultraviolet light but also in the visible-light region.
Co-reporter:Shenyong Shi, Qinghong Zhang, Hongzhi Wang, Yaogang Li
Progress in Natural Science: Materials International (June 2012) Volume 22(Issue 3) pp:224-230
Publication Date(Web):1 June 2012
DOI:10.1016/j.pnsc.2012.04.009
The 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) powder had three particle size distributions, while the fine one was lower than 100 nm. The 3Y-TZP compact was prepared by dry-pressing under pressures ranged from 10 to 30 MPa and then presintered at 1250 °C for 2 h. The matrix dry-pressed under the pressure of 20 MPa had a porosity of 16.7% and could be easily processed by computer aided design and computer aided manufacturing (CAD/CAM), and which had been infiltrated by the La2O3–Al2O3–SiO2 glass at 1200 °C for 4 h. The flexural strength and fracture toughness of the composite were 710.7 MPa and 6.51 MPa m1/2, respectively. The low shrinkage (0.3%) of the composite can satisfy the net-shape fabrication standard. XRD results illustrated that zirconia in the La2O3–Al2O3–SiO2 glass-infiltrated 3Y-TZP all-ceramic composite was mainly in the tetragonal phase. SEM and EDS results indicated that the pores of the matrix were almost filled by the La2O3–Al2O3–SiO2 glass.
Co-reporter:Jiabin Qi, Hao Xiong, Jie Zhang, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Journal of Alloys and Compounds (25 April 2017) Volume 702() pp:
Publication Date(Web):25 April 2017
DOI:10.1016/j.jallcom.2017.01.220
•The substrate of flexible Ti foil as photo-electrode is used.•A suitable process to fabricate the FDSSCs is achieved by using the release agent.•Uniform particles, good density and high porosity are achieved.•The process is in favor of commercialized mass production.Flexible dye-sensitized solar cells (FDSSCs) are dye-sensitized thin-film solar cells constructed on flexible substrate with the advantages of eco-friendly, ease of fabrication, low cost and light weight. FDSSCs exhibit extensive application prospect. Herein, FDSSCs were constructed by the roll-to-roll method using terpineol and silicone oil as the release agent. Three-dimensional profile measurement is taken directly on nanocrystalline-TiO2 photoanodes. The phase composition and surface micro-morphology indicate that relatively large grain sizes and uniform surface of TiO2 particles are obtained. A layer of amorphous SiO2 exists on the nanocrystalline-TiO2 photoanode owing to the release agent (silicon oil), which hinders electrons to travel, thus the photoelectric conversion efficiency is low. However, nanocrystalline-TiO2 photoanodes with uniform particles, good density and high porosity are achieved by using the release agent of terpineol, and the energy conversion efficiency of 2.97% was obtained.
Co-reporter:Qinghui Mu, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Sensors and Actuators B: Chemical (20 July 2011) Volume 155(Issue 2) pp:804-809
Publication Date(Web):20 July 2011
DOI:10.1016/j.snb.2011.01.051
Large arrays of one-dimensional uniform-sized TiO2 nanofibers (TNFs) were prepared through a template-free method, and used as a working electrode in a transparent microfluidic device made from poly (dimethyl siloxane) (PDMS) to perform efficient photoelectrocatalysis for rapid and undefiled determination of chemical oxygen demand (COD). Photoelectrochemical measurements were used to evaluate the response of TNFs to the intensity of exciting light and the applied potential bias. The photoelectrocatalysis of TNFs in PDMS-based microfluidic device exhibited excellent performance for determination of COD. The practical limit of determination of 0.95 mg/L COD with a working range of 0–250 mg/L was achieved. The relative standard deviation (RSD) was 1.85% for 10 repeated measurements of 0.3 mmol/L glucose with COD value of 57.6 mg/L.
Co-reporter:Zhongyuan He, Yaogang Li, Qinghong Zhang, Hongzhi Wang
Applied Catalysis B: Environmental (12 January 2010) Volume 93(Issues 3–4) pp:376-382
Publication Date(Web):12 January 2010
DOI:10.1016/j.apcatb.2009.10.011
Co-reporter:Yinben Guo, Yaogang Li, Qinghong Zhang and Hongzhi Wang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 6) pp:NaN1442-1442
Publication Date(Web):2017/01/12
DOI:10.1039/C6TC04771H
Inspired by the human eye, an electronic eye (e-eye) is a photodetector that senses optical signals. To solve the problems of power supply and the limitation of application only in the visible region, a self-powered, multifunctional e-eye for UV and IR light detection was developed. The e-eye harvests mechanical and thermal energy from the ambient environment by the triboelectric and thermoelectric effect to power itself. ZnO and RGO were chosen as active UV and IR photosensitive materials, respectively, and were vertically integrated into a single device with a multilayer structure. The self-powered, e-eye has good photoelectric properties. Moreover, it can distinguish UV and IR irradiation of different intensities individually or simultaneously through the generation of different electric signals, endowing the e-eye great with potential applications in portable/wearable UV and IR detection devices.
Co-reporter:Minwei Zhang, Chengyi Hou, Arnab Halder, Hongzhi Wang and Qijin Chi
Inorganic Chemistry Frontiers 2017 - vol. 1(Issue 1) pp:NaN60-60
Publication Date(Web):2016/09/29
DOI:10.1039/C6QM00145A
Paper is an attractively assembled form of materials and has accompanied our daily life almost everywhere. Two-dimensional layered materials, especially graphene, have unique intrinsic structures to be exploited for smart architecture of macroscopic papers that are offering many newly emerging applications. Research advances in graphene based papers in the past few years have created a new category of composite materials. This review aims at offering an up-to-date comprehensive summary of graphene-supported papers, with the emphasis on smart assembly and purpose-driven specific functionalization for their critical applications associated with sensing, environmental and energy technologies. The contents of this review are based on a balance combination of our own studies and selected research studies done by worldwide academic groups. We first give a brief introduction to graphene as a versatile building block and to the current status of research studies on graphene papers. This is followed by addressing some crucial methods of how to prepare graphene papers. We then summarize multiple possibilities of functionalizing graphene papers, membranes or films. Finally, we evaluate some key applications of graphene papers in the areas of chemical/electrochemical sensors, biomimetics and energy storage devices, just before leading to our concluding remarks and perspectives.
Co-reporter:Yunxin Gu, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 29) pp:NaN6056-6056
Publication Date(Web):2010/06/16
DOI:10.1039/C0JM00118J
Rod-like, uniform, and poorly aggregated BaSi2O2N2:Eu powders with tunable luminescence for white LEDs have been successfully synthesized by direct gas-reduction nitridation from the core-shell oxide (Ba,Eu)CO3@SiO2. Maximization of the contact surface between the reactants and minimization of diffusion distances improved the efficiency of the nitridation. Thus, the desired oxynitride phosphors were obtained at relatively low temperatures (around 1100–1200 °C). Under these conditions, the (Ba,Eu)CO3 cores melted into small seeds which decreased the particle size and promoted the oriented growth of BaSi2O2N2:Eu. The nucleation and subsequent crystal growth in (Ba,Eu)CO3@SiO2 were further discussed in the samples with different Ba/Si ratios. By controlling the nitridation process, tunable luminescence was achieved in the range of 490–530 nm. The low sedimentation rate of the phosphors from this route shows additional advantages in the LED packaging.
Co-reporter:Yunxin Gu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 44) pp:NaN17797-17797
Publication Date(Web):2011/10/11
DOI:10.1039/C1JM13351A
Oxynitride phosphor mat consisting of CaSi2O2N2:Eu nanofibers is prepared by electrospinning the fiber precursor and subsequent nitridation. As-prepared fiber precursor is smooth and uniform with a diameter of 400–600 nm. After removing organic templates and nitridation, the fiber morphology is well retained and a smooth phosphor mat consisting of uniform fiber network is obtained. X-Ray diffraction results confirm that a pure CaSi2O2N2 phase can be obtained at low temperature of around 1300 °C. Series of experiments simulating the LED working environment are conducted and the results confirm that the CaSi2O2N2:Eu nanofiber mat can keep high transmittance and strong emission intensity at the same time, which can be attributed to the uniform fiber arrangement in the nanostructure. Moreover, a new LED packaging process is attempted by using CaSi2O2N2:Eu nanofiber mat. Different colour temperatures can be obtained by employing phosphor mats with different thicknesses. Phosphor agglomeration in the conventional packaging process is avoided, and the efficacy and light homogeneity of the lamp are significantly improved.
Co-reporter:Chengyi Hou, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 28) pp:NaN10517-10517
Publication Date(Web):2011/06/09
DOI:10.1039/C1JM11086A
Aqueous-dispersed graphene/Fe3O4 hybrids are prepared using a two-step method. Functional microgels composed of the poly(N-isopropylacrylamide) (PNIPAAm) and the as-prepared graphene/Fe3O4 hybrids are synthesized in a microfluidic reactor for the first time. The microgel exhibits a good response to an external magnet and near-infrared (NIR) laser irradiation, indicating that it could be used as a light-driven and magnetic controlled switch for applications in microreactors.
Co-reporter:Dongyun Ma, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 32) pp:NaN16639-16639
Publication Date(Web):2012/07/03
DOI:10.1039/C2JM32784H
Vertically oriented WO3 nanoflakes woven from nanowires were obtained using a crystal-seed-assisted hydrothermal technique on a glass substrate coated with fluorine-doped tin oxide (FTO). Investigation of the growth process revealed that two types of nanowire, along the (100) and (002) planes, respectively, were formed in the early stages. In the presence of oxalic acid and urea, these nanowires were then interwoven to give a flake-like nanofabric. This process is similar to weaving on a loom, in which the two types of nanowire act as “warp and weft threads” and the oxalic acid and urea act as the “shuttle”. The as-prepared films exhibit tunable transmittance modulation under different voltages, and repeated cycling between the coloration and bleaching states has no deleterious effect on their electrochromic performance after 1000 cycles. A larger optical modulation of 68% at 632.8 nm at a potential of −3.0 V, faster switching speeds of tc(90%) = 9.3 s and tb(90%) = 5.7 s for coloration and bleaching, respectively, and a higher coloration efficiency of 134.4 cm2 C−1 than those previously reported for the electrochromic performances of nanostructured films were achieved for this self-weaving nanoflake film.
Co-reporter:Chengyi Hou, Yourong Duan, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 30) pp:NaN14996-14996
Publication Date(Web):2012/05/28
DOI:10.1039/C2JM32255B
For biomimetic applications, an artificial material is needed to be self-healing, electroactive and bio-applicable. Herein we report a strategy to build a graphene–poly(N,N-dimethylacrylamide) (PDMAA) cross-linking structure based on graphene networks. The obtained hydrogel exhibits good neural compatibility, high conductivity, low impedance and efficient near-infrared-triggered photothermal self-healing behaviour owing to its unique 3-dimensional graphene–PDMAA cross-linking networks. The results indicate that the graphene–PDMAA hydrogel has potential for application as an artificial tissue.
Co-reporter:Yuanlong Shao, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN1251-1251
Publication Date(Web):2012/12/05
DOI:10.1039/C2TC00235C
We demonstrate a simple method for preparing flexible, free-standing, three-dimensional porous graphene/MnO2 nanorod and graphene/Ag hybrid thin-film electrodes using a filtration assembly process. These graphene hybrid films, which accelerate ion and electron transport by providing lower ion-transport resistances and shorter diffusion-distances, exhibit high specific capacitances and power performances, and excellent mechanical flexibility. A novel asymmetric supercapacitor (SC) has been fabricated by using a graphene/MnO2 nanorod thin film as the positive electrode and a graphene/Ag thin film as the negative electrode. These devices exhibit a maximum energy density of 50.8 W h kg−1 and present a high power density of 90.3 kW kg−1, even at an energy density of 7.53 W h kg−1. The bent hybrid nanostructured asymmetric SC is connected to spin a fan, which also proved the high power density of the fabricated asymmetric SCs. These results suggest that such asymmetric graphene/MnO2 nanorod and graphene/Ag hybrid thin-film architectures are promising for next-generation high-performance flexible supercapacitors.
Co-reporter:Hao Xiong, Yichuan Rui, Yaogang Li, Qinghong Zhang and Hongzhi Wang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 28) pp:NaN6854-6854
Publication Date(Web):2016/06/27
DOI:10.1039/C6TC02238C
Lead halide perovskite solar cells with high efficiency have recently attracted tremendous attention. However, the poor stability of perovskite materials has hindered their practical applications. Here, we presented a hydrophobic agent, fluoroalkyl silane, to modify both the light absorbing layer and the hole transport layer. In the presence of a hydrophobic coating, we obtained a stable perovskite solar cell with less hysteresis between the forward sweep and the reverse sweep in air. The effect of fluoroalkyl silane concentration on the stability was investigated; with an optimized 2.0 wt% fluoroalkyl silane solution treatment, the efficiency of perovskite solar cells has reached over 12.0 ± 0.4%. Moreover, for those perovskite solar cells that are exposed to air with about 50% relative humidity, the efficiency was maintained at around 12% for a duration of more than 500 h, while the efficiency of those without hydrophobic coating sharply decreased from about 12% to 1% in a duration of 250 h.
Co-reporter:Kerui Li, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 24) pp:NaN5857-5857
Publication Date(Web):2016/05/23
DOI:10.1039/C6TC01516F
Mechanical and electrochemical stability issues of electrode materials have been long-standing obstacles restricting the development of highly flexible electrochromics. Herein, a lightweight, highly bendable and foldable electrochromic (EC) film is realized through the construction of mechanically and electrochemically stable bilayer nanowire networks (BNNs) on ultra-thin polyethylene terephthalate (PET) substrates. These BNNs composed of silver nanowires (AgNWs) and W18O49 nanowires (W18O49NWs) are prepared using a facile and continuous spray-coating method. An alginic acid/poly(dopamine) complex (Aa–PDA) and a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer are used as a binder and a charge balancing layer, respectively, to enhance the interfacial and structural stability of nanowires and prevent the electrochemical corrosion of AgNWs. These optimized and highly flexible EC films exhibit good optical contrast, high coloration efficiency (up to 118.1 cm2 C−1), highly enhanced electrochemical stability and excellent structural stability even after 500 bending or 100 folding cycles. Moreover, EC films per square centimeter weigh less than 2.3 mg. The spray-coating method is easily controlled and allowed for convenient patterning, which is important for real-life applications.
Co-reporter:De Zhao, Gang Wang, Zhongyuan He, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 20) pp:NaN4281-4281
Publication Date(Web):2015/04/22
DOI:10.1039/C5TB00324E
Three kinds of micro/nanostructured NiO arrays were constructed in confined microchannels via a facile and template-free microfluidic chemical fabrication method. Bovine serum albumin (BSA) and bovine hemoglobin (BHb) with different isoelectric points (IEPs) were chosen as the model proteins to test the absorption ability of NiO-modified microchannels for abundant proteins via electrostatic interaction and affinity interaction. The influences of the pH and ionic strength of the protein solution, the residence time of protein solution in the microchannels, zeta potentials and morphologies of nickel oxide on the protein absorption behavior of the modified microchannels were all studied. The NiO nanosheet array-modified microchannels could almost absorb all of the target proteins when the protein solution (500 μg mL−1) resided in the microchannel for 120 s without separation. The excellent protein absorption ability of NiO nanosheet array-modified microchannels could be attributed to their high zeta potential and more absorption sites induced by the macroporous structure consisting of large nanosheets. Moreover, the NiO nanosheet array-modified microchannels also exhibited excellent selective absorption ability for hemoglobin from a protein mixture and human blood samples owing to the strong affinity interaction between nickel and the histidine residues of hemoglobin. Therefore, the NiO nanosheet array-modified microchannels showed promise for application in proteomics.
Co-reporter:Dongyun Ma, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 3) pp:NaN691-691
Publication Date(Web):2012/10/22
DOI:10.1039/C2TA00090C
We have demonstrated that vertically aligned WO3 nanostructure films can be fabricated on FTO-coated glass substrates using a template-free hydrothermal technique. Detailed mechanistic studies revealed that a variety of WO3 nanostructures—including nano-bricks, 1D nanorods and nanowires, and 3D nanorod-flowers—could be obtained by tuning the composition of the precursor solution, where the urea content and solvent composition played important roles in controlling the shape and size of the WO3 nanostructures, respectively. These nanostructured films exhibited enhanced electrochromic performance, and we drew a map for the correlation between the morphology and the electrochromic performance of the as-synthesized WO3 films. Due to the large tunnels in the hexagonally structured WO3, and the large active surface area available for electrochemical reactions, a large optical modulation of 66% at 632.8 nm and a potential of −2.0 V, fast switching speeds of 6.7 s and 3.4 s for coloration and bleaching, respectively, and a high coloration efficiency of 106.8 cm2 C−1 are achieved for the cylindrical nanorod array film.
Co-reporter:Dongyun Ma, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 33) pp:NaN13549-13549
Publication Date(Web):2014/06/10
DOI:10.1039/C4TA01722F
The high performance of organic/inorganic hybrid materials relies largely on a scrupulous design of nanoarchitectures so that the organic and inorganic phases can work synergistically. We present a powerful two-step solution-based method for the fabrication of hierarchical metal oxide/conducting polymer heterostructured nanoarrays. Demonstrated examples include different nanostructures (nanorod arrays, nanorod-based networks and nanoplate arrays) of metal oxides (WO3 and NiO) and PANI (nanostubs, nanoparticles and nano-wrinkles). Given the unique composition and architecture, the hierarchical NiO/PANI nanoplate arrays show reversible multicolor changes, fast switching speeds of 90 and 120 ms for coloration and bleaching states, respectively, and a superior coloration efficiency of 121.6 cm2 C−1 under a low voltage of 1.2 V. Additionally, the application of the NiO/PANI nanoplate array coated FTO glass causes a temperature difference of 7–7.6 °C under different ambient temperatures, making it very attractive for potential applications in energy-saving smart windows. Our strategy paves the way for the design and synthesis of hierarchical metal oxide/conducting polymer nanoarrays with enhanced properties for new applications.
Co-reporter:Shenglong Shang, Zhifu Liu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 20) pp:NaN11097-11097
Publication Date(Web):2015/04/17
DOI:10.1039/C5TA00775E
An elastic, structurally colored fiber with reversible structural color is described in this article. Using an external magnetic field, Fe3O4@C superparamagnetic colloidal nanocrystal clusters (SCNCs) formed one-dimensional chain-like photonic crystal structures and were embedded in a polyacrylamide matrix. When the fiber was stretched/squeezed in the horizontal direction, the size of the fiber reduced/increased in the vertical direction. As a result, the distance between each sphere in chain-like structures can be reversibly changed through the elastic deformation of the matrix, and the structurally colored fiber displays brilliant colors, ranging from red to green as the mechanical strain changes, which can be clearly observed by the naked eye. The reflection peak can be tuned from 637 nm to 515 nm as a function of fiber extrusion or elongation. The novel structurally colored fiber is expected to have some important applications such as the substitution of some fiber-based wearable electronic strain sensors because this fiber does not require any additional devices to provide energy.
Co-reporter:Qiuwei Shi, Chengyi Hou, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 18) pp:NaN9889-9889
Publication Date(Web):2015/03/27
DOI:10.1039/C5TA00920K
Graphene foam with three-dimensional (3D) networks was formed following removal of the undesirable toxic iodide induced in a HI reduced GO film through NIR light irradiation via a near infrared (NIR) light irradiation method under ambient laboratory conditions. Compact reduced graphene oxide films were used as the precursors which were fabricated through vacuum filtration and HI reduction. A series of graphene foams which have alterable pore sizes ranging from a few to hundred micrometers rapidly formed under NIR light irradiation at different power densities. The graphene foam has an ultimate tensile strength of about 15.3 MPa and could be compressed at a very large strain (ε = 60%) for 200 cycles without significant plastic deformation or degradation in compressive strength. This 3D graphene network is hydrophobic and showed high absorbing abilities for organic liquids. The adsorbed oil weight is up to about 27 times the weight of graphene foam after being immersed in an oil–water mixture for two minutes, and 87.2% of adsorbed oil could be squeezed out and recycled. This process is highly repeatable, which makes our product a potential candidate for removal and recycling of oil for environmental protection.
Co-reporter:Zhifu Liu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Chemical Communications 2011 - vol. 47(Issue 48) pp:NaN12803-12803
Publication Date(Web):2011/10/31
DOI:10.1039/C1CC15588A
Structural colored fiber was fabricated by an isothermal heating evaporation-induced self-assembly method. Under ambient white light illumination, the fibers appear colored due to optical reflectance, which is determined by the lattice constants of the photonic crystals. By controlling the size and layers of the silica nanospheres, the fiber color can be changed.
Co-reporter:Qiuwei Shi, Chengyi Hou, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Chemical Communications 2016 - vol. 52(Issue 34) pp:NaN5819-5819
Publication Date(Web):2016/03/16
DOI:10.1039/C6CC01590E
A novel all-solid electrically controllable Au@graphene oxide (GO) actuator with a bilayer structure is reported to address many of the limitations of traditional electrical-driven materials including complicated layouts and high electric fields. Specifically, the obtained Au@GO actuator possesses electrolyte-free, real time controlled actuation and patterning capabilities.
Co-reporter:Yuanlong Shao, Maher F. El-Kady, Lisa J. Wang, Qinghong Zhang, Yaogang Li, Hongzhi Wang, Mir F. Mousavi and Richard B. Kaner
Chemical Society Reviews 2015 - vol. 44(Issue 11) pp:NaN3665-3665
Publication Date(Web):2015/04/22
DOI:10.1039/C4CS00316K
The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors.
Co-reporter:Haizeng Li, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 29) pp:NaN11310-11310
Publication Date(Web):2014/05/21
DOI:10.1039/C4TA01803F
Self-seeded hydrothermal process could eliminate the grain boundaries existing in the nanocrystalline base layer, which speeds up electron transport to the fluorine-doped tin oxide (FTO) glass and promotes electron transfer efficiency. This report highlights the hierarchical nest-like WO3·0.33H2O film grown directly on bare FTO glass without a seed layer prepared in advance. The film exhibits highly improved electrochromic performances.
Co-reporter:Haizeng Li, Jingwei Chen, Mengqi Cui, Guofa Cai, Alice Lee-Sie Eh, Pooi See Lee, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 1) pp:NaN38-38
Publication Date(Web):2015/11/16
DOI:10.1039/C5TC02802G
Ultrathin tungsten molybdenum oxide nanoparticle films were fabricated from aqueous ink by a spray coating technique. With the in situ heating of the hot plate during the spray coating process, the detrimental effects of oxygen vacancies on electrochromic (EC) materials could be eliminated. The spray coated ultrathin films exhibit higher contrast than the drop casted films, which would provide a versatile and promising platform for energy-saving smart (ESS) windows, batteries, and other applications.
Co-reporter:Pengtao Shao, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2011 - vol. 21(Issue 1) pp:NaN156-156
Publication Date(Web):2010/10/22
DOI:10.1039/C0JM01878C
The aqueous synthesis of color-tunable and stable Mn2+-doped ZnSe quantum dots (Mn:ZnSe d-dots) via a nucleation-doping strategy was realized in a three-necked flask and the photoluminescence (PL) peak position was easily tuned from 572 nm to 602 nm by prolonging the epitaxial-growthg time. The chemical stability of the resulting d-dots is much better than that of CdTevia an aqueous synthesis. Separation of nucleation and growth of crystallization, and multiple-step-injection of both zinc precursor and 3-mercaptopropionic acid (MPA) stabilizing reagent, were employed to realize a balanced, mutually diffused interface and a pure ZnSe shell. The resulting nanocrystals show excellent optical properties, implying that nanocrystals with high quality could also be achieved via aqueous synthesis.
Co-reporter:Pengtao Shao, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 44) pp:NaN17977-17977
Publication Date(Web):2011/10/13
DOI:10.1039/C1JM12128F
Mn-doped ZnSe nanocrystals (Mn:ZnSe d-dots) that emit white light were synthesized in aqueous media in microfluidic reactors. White light emission from Mn:ZnSe d-dots was a result of combined emission of blue light (emission from non-coordinated surface selenium sites) and yellow light (4T1 → 6A1 emission from Mn2+ ions). Emission from non-coordinated surface selenium sites was realized by adjusting the ratio of the flow volumes of [Zn]/[Mn] and the mass of stabilizer added. Photoluminescence from the Mn:ZnSe d-dots was easily tuned from 580 to 602 nm by regulating flow volume. Under the optimal experimental conditions, Mn:ZnSe d-dots that emit white light with a quantum yield of about 10.2% were fabricated.
Co-reporter:Xiaoxu Zhu, Qinghong Zhang, Yaogang Li and Hongzhi Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 9) pp:NaN1771-1771
Publication Date(Web):2010/01/14
DOI:10.1039/B922873J
A microfluidic reactor heated by microwave (MW) irradiation was utilized for the first time to prepare LaF3/LaPO4:Ce,Tb nanocrystals (NCs) using ethylene glycol (EG) as solvent. Redispersible and water-soluble LaF3 nanoparticles with a mean diameter of 4.5 nm, and LaPO4 nanorods with a length of 60–70 nm and diameter of 10–15 nm were simply obtained. Dielectric heating by the irradiation and the special MW effect combined with the microfluidic reactor accelerate the nucleation stage and promote the growth stage of NCs, which results in improved luminescent properties and yields of products.
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