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:Yinben Guo;Qinghong Zhang;Hongzhi Wang
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: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: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: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: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:Quanfeng Tang, Haizeng Li, Yanfang Yue, Qinghong Zhang, Hongzhi Wang, Yaogang Li, Pei Chen
Materials & Design 2017 Volume 118(Volume 118) pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.matdes.2017.01.033
•The gel electrolyte with reduced anodic reaction potential was introduced in electrochromic devices.•The gel electrolyte exhibits high ionic conductivity due to the addition of charge carriers from ionic liquid.•Electrochromic devices assembled with the gel electrolyte exhibit higher contrast under small applied potentials.The electrolyte plays an important role in an electrochromic device (ECD), and an ideal electrolyte can greatly improve the electrochromic performance of the device. Here, we report the preparation of a 1-Ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4)-doped Poly(methyl methacrylate) (PMMA)-based gel electrolyte for electrochromic applications. By the doping of the [Emim]BF4, the ionic conductivity of the gel electrolyte is improved (2.9 × 10− 3 S/cm at room temperature and 10− 2 S/cm at 40 °C). Most importantly, the addition of the [Emim]BF4 could reduce the anodic reaction potentials in an ECD, which could enable ECD bleaching at smaller applied voltages and avoid the degradation of optical modulation induced by ion-trapping in tungsten oxide (WO3) films. This novel electrolyte provides a promising platform for low anodic reaction potential electrochromic devices.Download high-res image (92KB)Download full-size image
Co-reporter:Yuanlong Shao;Maher F. El-Kady;Cheng-Wei Lin;Guanzhou Zhu;Kristofer L. Marsh;Jee Youn Hwang;Qinghong Zhang;Hongzhi Wang;Richard B. Kaner
Advanced Materials 2016 Volume 28( Issue 31) pp:6719-6726
Publication Date(Web):
DOI:10.1002/adma.201506157
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: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: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: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: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: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: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: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: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:Weixin Heng, Wei Zhang, Qinghong Zhang, Hongzhi Wang and Yaogang Li
RSC Advances 2016 vol. 6(Issue 55) pp:49824-49830
Publication Date(Web):16 May 2016
DOI:10.1039/C6RA09230F
In this work, a hierarchical TiO2 nanotube (H-TNTs) electrode was successfully fabricated via the anodization of a titanium sheet followed by a hydrothermal process. TiO2 nanoparticles were successfully deposited on the surface of the TiO2 nanotubes (TNTs) which can enhance the light-harvesting capability and surface area of TNTs. In comparison with the pure TNTs, the H-TNT electrode showed a great enhancement in the photocurrent response. Subsequently, the H-TNT electrode was put into a microfluidic device made from polymethyl methacrylate (PMMA) for mineralization of organic compounds. Photocatalytic results showed that a COD detection limit of 1 mg L−1 COD and a linear range of 0–300 mg L−1 COD were achieved by the microfluidic device.
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: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: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: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: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: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: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: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: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:Hailei Zhao, Bo Cui, Zhenhua Chen, Hongzhi Wang, Qinghong Zhang and Yaogang Li
RSC Advances 2015 vol. 5(Issue 123) pp:101287-101292
Publication Date(Web):17 Nov 2015
DOI:10.1039/C5RA18549A
Pure inorganic materials are expected to find applications in various fields including energy-efficient and environmental-friendly soft display technologies, thereby requiring them to operate effectively while being bent or stretched. In the present study, excellent mechanical flexibility properties were successfully imparted into conventionally fragile inorganic materials using a nanobelt network design. Specifically, organic–inorganic composite materials were engineered into considerably long and continuous nanobelts using a simple electrospinning process. The composites were then subjected to calcination and nitridation processes to produce highly fluorescent inorganic (Si-based) membranes with high flexibility. The synthesized nanobelts exhibit high aspect ratios and well-defined rectangular cross-sections, and display excellent mechanical flexibility. The nanobelts could be bent to a minimum curvature radius down to 1 mm. Furthermore, the nanobelts incur no visible damage after 500 cycles of bending to a radius of 1 cm. Under an applied strain of 6% for 500 cycles, the flexible SiO2-based fluorescent nanobelt membrane maintained a high strength of 6.0 MPa. Moreover, the photoluminescence intensity of the free-standing fluorescent nanofibrous inorganic membranes featured excellent environmental, thermal and mechanical cyclic stability. The current findings strongly indicate the great potential of the engineered fluorescent inorganic membranes as fluorescent materials in flexible display technologies and the remote packaging of LED.
Co-reporter:Qi Liu, Qiuwei Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
RSC Advances 2015 vol. 5(Issue 58) pp:47074-47079
Publication Date(Web):12 May 2015
DOI:10.1039/C5RA08431H
Graphene, the last representative of sp2 carbon materials, has been an ideal material platform for constructing flexible electronic devices. Exploring a new method to fabricate high-quality graphene films with a more porous structure is a key for flexible electronic devices to achieve higher performance. A flexible solid-state supercapacitor based on a 3-dimentional graphene film electrode is fabricated via filtration and laser irradiation method. The fabricated films with excellent mechanical properties display high electrical conductivity (8.53 Ω) and improved electrochemical performance (185 F g−1). This 3-dimensional film is freestanding, which can thus be used directly as supercapacitor electrodes without external current collectors or binders that are often used in commercial supercapacitors. Moreover, the films maintain excellent electrochemical properties under high stress and thus hold promise for being widely used in various energy storage devices.
Co-reporter:Haizeng Li, Jinmin Wang, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
RSC Advances 2015 vol. 5(Issue 1) pp:196-201
Publication Date(Web):24 Nov 2014
DOI:10.1039/C4RA12099J
Tungsten trioxide hydrate (WO3·0.33H2O) films with different morphologies were directly grown on a fluorine doped tin oxide (FTO) substrate. With the directing effect of a seed layer, WO3·0.33H2O thin films composed of nanosheet structures could be selectively synthesized. The effect of urea was also discussed in this paper. The crystal-seed-assisted film grown with urea as a capping agent exhibits efficient electrochromic performances.
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:Chengyi Hou;Hongzhi Wang;Qinghong Zhang;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;Hongzhi Wang;Qinghong Zhang
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: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: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: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:Chengyi Hou, Haocheng Quan, Yourong Duan, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Nanoscale 2013 vol. 5(Issue 3) pp:1227-1232
Publication Date(Web):07 Dec 2012
DOI:10.1039/C2NR32938G
We report a Cu2O nanocrystal–reduced graphene oxide hybrid that is dispersible in water and has anticancer activity under both visible and near-infrared light irradiation. In contrast to the highly efficient killing of both normal and cancer cells initiated by the photothermal effect, the photocatalytic effect of this material results in the selective killing of cancer cells under visible light irradiation. These results have implications for safe and widely applicable cancer therapy agents.
Co-reporter:Dongyun Ma, Guoying Shi, Hongzhi Wang, Qinghong Zhang and Yaogang Li
Nanoscale 2013 vol. 5(Issue 11) pp:4808-4815
Publication Date(Web):28 Mar 2013
DOI:10.1039/C3NR00887H
We have demonstrated that thin films of hierarchical NiO microflakes assembled from nanoleaves can be grown directly on FTO-coated glass substrates using a facile and template-free hydrothermal technique. This hierarchical structure holds the advantages of both nanometre-sized building blocks and microsized assemblies. Thus, the films exhibit highly enhanced electrochromic performances and cyclic stability due to their high surface area and good electrochemical stability. Moreover, a complementary electrochromic device combining the hierarchical NiO microflake film with a self-weaving WO3 nanoflake film is fabricated to further improve the electrochromic performance. As a result, the complementary electrochromic device shows a high optical modulation (73.2% at 550 nm), large coloration efficiency (146.9 cm2 C−1 at 550 nm by applying a low coloration voltage of −1.0 V) and fast switching responses with a coloring time of 1.8 s and a bleaching time of 3.2 s. It is also observed that there is no significant degradation of the electrochromic properties after 2000 continuous coloration/bleaching cycles, making it attractive for practical applications.
Co-reporter:Zhifu Liu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
Nanoscale 2013 vol. 5(Issue 15) pp:6917-6922
Publication Date(Web):17 May 2013
DOI:10.1039/C3NR01766D
Structurally colored fiber was fabricated by an electrophoretic deposition method under a circinate electric field. These fibers exhibit structural color, based on the external field-assembly of charged PMMA microspheres on the surface of the electroconductive carbon fiber, with reflectance spectra stretch-tunable in the 430–608 nm, which are determined by the lattice constants of the photonic crystals. Also, the influence of applied voltage, deposition time and electroconductivity on the number of deposited layers and efficiency were studied. In addition, we further developed a horizontal and continuous process to fabricate a long range structurally colored fiber. And the method is a drastic acceleration in comparison with the gravity sedimentation technique that needs weeks or even months, and it would be fast and facile for the further study of structural color on the surface of the fiber. The process may be used to simulate the conventional fiber coloration process. Such elastically tuned structurally colored fibers are of interest for many applications.
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: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: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: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:Chengyi Hou;Leipeng Ji;Qinghong Zhang;Hongzhi Wang
Journal of Applied Polymer Science 2013 Volume 127( Issue 4) pp:2422-2426
Publication Date(Web):
DOI:10.1002/app.37944
Abstract
Multiwalled carbon nanotubes (MWCNTs)/poly(N-isopropylacrylamide-co-acrylic acid) composite microhydrogels are simply synthesized with controllable size distribution via a microfluidic reactor system. Monomers (N-isopropylacrylamide and acrylic acid) are rapidly copolymerized (about 3 s) with the embedding of nanoscaled inorganic materials (MWCNTs and hectorites) in microfluidic channels. MWCNTs/hectorites act as “molecular heater” and inorganic crosslinkers in this hydrogel system. As a result, microminiaturization, multifunctionalizaion, and modification of traditional polymer hydrogels are realized simultaneously. Fourier transform infrared spectroscopy is used to confirm polymerization and environment-sensitive tests are done as well. The resultant microgels exhibit dual near-infrared and pH response with good reversibility, indicating their potential applications in microreactor fields. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
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: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: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, 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:Bin Wu, Qinghong Zhang, Hongzhi Wang and Yaogang Li
CrystEngComm 2012 vol. 14(Issue 6) pp:2094-2099
Publication Date(Web):12 Jan 2012
DOI:10.1039/C2CE06366B
A novel solvothermal route has been developed to synthesize mondispersed and different mophologies of Eu-doped CaTiO3 phosphors including magic-column spherical, magic-cube spherical and polyhedral shaped, using a mixture of ethylene glycol (EG) and ethylenediamine (EDA). By tuning the solvent ratio, the method exhibited excellent control over the morphology of CaTiO3:Eu3+, and magic-column spherical phosphors have higher luminous intensities than magic-cube spherical and polyhedral shaped phosphors. The synthesized phosphors had higher luminous intensity and better packing properties than those obtained by a solid-state method. The phosphors showed strong red emissions, corresponding to the 5D0 → 7F2 (617.6 nm) transition of Eu3+ under near-ultraviolet excitation (398.4 nm). X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescent (PL) analyses were used to characterize the structure, morphology and luminous performance of CaTiO3:Eu3+ phosphors.
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: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: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:Xuecheng Chen, Chengyi Hou, Qinghong Zhang, Yaogang Li, Hongzhi Wang
Materials Science and Engineering: B 2012 Volume 177(Issue 13) pp:1067-1072
Publication Date(Web):1 August 2012
DOI:10.1016/j.mseb.2012.05.001
Co1−xNixFe2O4/graphene nanocomposites were synthesized through a one-step solvothermal method. The as-synthesized products were characterized by X-ray powder diffraction, field emission scanning microscopy, transmission electron microscope, and high-resolution transmission electron microscope. The results show that the Co1−xNixFe2O4 nanoparticles are uniformly dispersed on graphene sheets. The dependence of structure, magnetic and electrical properties of Co1−xNixFe2O4/graphene nanocomposites on the Ni2+ concentration and the graphene content were also studied. The saturation magnetization and electrical conductivity of the as-prepared products reached 51.82 emu/g and 1.00 × 102 S/m, respectively.Highlights► Multiple doping Fe3O4 ferrite/graphene with Co2+ and Ni2+ was prepared. ► An efficient and environmentally friendly one-step solvothermal method was used. ► The magnetic and electrical properties of the productions are excellent and controllable.
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, 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: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: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: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: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: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: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: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: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: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:Zhongyuan He;Qinghong Zhang;Hongzhi Wang
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: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: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: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: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: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: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: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:Hui Yu;Xiaohua Gu;Xinyuan Shen;Yourong Duan
Journal of Applied Polymer Science 2009 Volume 112( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/app.29643
Abstract
This study presented the investigations on the synthesis of a novel biodegradable block copolymer of pluronic-b-poly(L-lysine) (pluronic-b-PLL), which combined the characteristics of aliphatic polyester and poly(amino acids). The synthesis work started with end-capping of pluronic with N-t-butoxycarbonyl-L-phenylalanine using dicyclohexylcarbodiimide in the presence of 4-dimethylaminopyridine, followed by a deprotection process to obtain the amino-terminated pluronic; the new primary amino group in the modified pluronic initiated ring-opening polymerization of amino acid N-carboxyanhydride, which afforded the pluronic-b-poly(Nε-(Z)-L-lysine) block copolymer. Finally, removal of the side-chain Nε-(carbonybenzoxy) end protecting groups yields the block copolymer of pluronic-b-PLL. The products were characterized by 1H-NMR, FTIR, DSC, and GPC. The block copolymer micelle containing the anticancer drug paclitaxel was prepared by the double emulsion method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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: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:Yourong Duan;Jinping Xu;Yunzhu Lin;Hui Yu;Tao Gong;Zhirong Zhang
Journal of Biomedical Materials Research Part A 2008 Volume 87A( Issue 2) pp:515-523
Publication Date(Web):
DOI:10.1002/jbm.a.31784
Abstract
To develop an intravenous nanoparticle delivery system for a cancer drug (i.e., DHAQ, mitoxantrone), the synthesis of a biodegradable polyester polymer with hydrophilic polyethylene glycol chains, preparation of DHAQ-loaded nanoparticles from such polymer and biodistribution of the drug-loaded particles were investigated in this article. Biodegradable monomethoxy poly(ethylene glycol)-poly (lactide-co-glycolide)-monomethoxy poly(ethylene glycol) (MeO-PEG-PLGA-PEG-OMe, PELGE) copolymers were synthesized by ring-opening polymerization as the drug carriers. A double emulsion method with dextran-70 as an emulsifier was employed to prepare the nanoparticles. DHAQ-PELGE nanoparticles and free DHAQ were employed for the in vivo biodistribution studies after intravenous administration through the tail veins in mice. At various time intervals, the mice were sacrificed and several organs and tissues harvested, including hearts, livers, spleens, lungs, kidneys, and blood. The DHAQ concentrations in the collected tissues and plasmas were determined using high performance liquid chromatography. The DHAQ concentrations in mice plasmas in the experimental groups were significantly higher than those in the control group and 3.72% of total administrations dosages (TAD) of these particles with DHAQ remained in circulation even 96 h after intravenous injection. Compared with the free DHAQ, DHAQ-loaded PELGE nanoparticles had longer circulation properties. Further research should be done for intravenous injection of this material as drug carriers. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Co-reporter:Xiao-Jun Zhou, Guo-Jun Zhang, Yao-Gang Li, Yan-Mei Kan, Pei-Ling Wang
Materials Letters 2007 Volume 61(4–5) pp:960-963
Publication Date(Web):February 2007
DOI:10.1016/j.matlet.2006.06.024
ZrB2–SiC–C ultra high temperature ceramics (UHTCs) have been produced by hot pressing pyrolyzed mixtures of ZrB2 and polycarbosilane (PCS). Samples with SiC contents of 0%, 5% and 16% in volume derived from PCS were prepared. The phase composition, microstructure and mechanical properties were characterized for composites hot pressed at 2073 K for 60 min under the pressure of 20 MPa in an argon atmosphere. Analysis showed that the addition of PCS improved the relative density from 78% (without PCS addition) to ∼ 100% (with 16% SiC derived from PCS addition). Hardness and fracture toughness of the composite were also improved.
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: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: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: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: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: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: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: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: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: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: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: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: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: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: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, 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: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: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: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.
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.
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