Co-reporter:Xuanliang Zhao, Yu Long, Tingting Yang, Jing Li, and Hongwei Zhu
ACS Applied Materials & Interfaces September 6, 2017 Volume 9(Issue 35) pp:30171-30171
Publication Date(Web):August 21, 2017
DOI:10.1021/acsami.7b09184
Temperature and moisture are critical factors for both the environment and living creatures. Most temperature sensors and humidity sensors are rigid. It still remains an unsolved problem to fabricate a flexible sensor that can easily detect temperature and humidity at the same time. In this work, we made a flexible multifunctional temperature and humidity sensor from graphene woven fabrics. The integrated sensor could measure temperature and humidity simultaneously. The temperature-sensing part and the humidity-sensing part were stacked in layer structure, occupying little space and showing good flexibility while exhibiting high sensitivity and very little mutual interference. The different factors that affected the sensing properties of the sensor were examined. The integrated sensor was successfully utilized in several real life application scenarios, which showed its potential for wider use in environment sensing and health monitoring.Keywords: flexible; graphene; humidity; sensors; temperature;
Co-reporter:Tingting Yang, Xin Jiang, Yujia Zhong, Xuanliang Zhao, Shuyuan Lin, Jing Li, Xinming Li, Jianlong Xu, Zhihong Li, and Hongwei Zhu
ACS Sensors July 28, 2017 Volume 2(Issue 7) pp:967-967
Publication Date(Web):July 5, 2017
DOI:10.1021/acssensors.7b00230
Profuse medical information about cardiovascular properties can be gathered from pulse waveforms. Therefore, it is desirable to design a smart pulse monitoring device to achieve noninvasive and real-time acquisition of cardiovascular parameters. The majority of current pulse sensors are usually bulky or insufficient in sensitivity. In this work, a graphene-based skin-like sensor is explored for pulse wave sensing with features of easy use and wearing comfort. Moreover, the adjustment of the substrate stiffness and interfacial bonding accomplish the optimal balance between sensor linearity and signal sensitivity, as well as measurement of the beat-to-beat radial arterial pulse. Compared with the existing bulky and nonportable clinical instruments, this highly sensitive and soft sensing patch not only provides primary sensor interface to human skin, but also can objectively and accurately detect the subtle pulse signal variations in a real-time fashion, such as pulse waveforms with different ages, pre- and post-exercise, thus presenting a promising solution to home-based pulse monitoring.Keywords: graphene; highly sensitive; pulse diagnosis; strain sensor; wearable;
Co-reporter:Chunyan Li;Zhen Li;Kunlin Wang;Jinquan Wei;Xiao Li;Han Zhang;Pengzhan Sun;Dehai Wu
The Journal of Physical Chemistry C August 26, 2010 Volume 114(Issue 33) pp:14008-14012
Publication Date(Web):Publication Date (Web): August 4, 2010
DOI:10.1021/jp1041487
Freestanding carbon-based composite thin films, consisting of a carbon nanotube network patched with graphene sheets, were assembled by a solid-phase layer-stacking approach with ethanol wetting. The composite films are highly flexible, transparent, and conductive, showing a sheet resistance of 735 Ω/sq at 90% transmittance (at 550 nm). Under AM1.5 illumination, heterojunction solar cells made from the composite films and n-type silicon show a power conversion efficiency of up to 5.2%.
Co-reporter:Pengzhan Sun;Kunlin Wang;Takayoshi Sasaki;Xueyin Bai;Renzhi Ma
Science Advances 2017 Volume 3(Issue 4) pp:e1602629
Publication Date(Web):14 Apr 2017
DOI:10.1126/sciadv.1602629
Nanosheets exhibit high and anisotropic hydroxyl ion conductivity, promising potentials in energy or environment applications.
Co-reporter:Shuying Wang;Li Zhang;Xiao Li;Changli Li;Rujing Zhang;Yingjiu Zhang
Nano Research 2017 Volume 10( Issue 2) pp:415-425
Publication Date(Web):2017 February
DOI:10.1007/s12274-016-1301-9
Cost-effective hydrogen production via electrolysis of water requires efficient and durable earth-abundant catalysts for the hydrogen evolution reaction (HER) over a wide pH range. Herein, we report sponge-like nickel phosphide–carbon nanotube (NixP/CNT) hybrid electrodes that were prepared by facile cyclic voltammetric deposition of amorphous NixP catalysts onto the threedimensional (3D) porous CNT support. These compounds exhibit superior catalytic activity for sustained hydrogen evolution in acidic, neutral, and basic media. In particular, the NixP/CNT electrodes generate cathodic currents of 10 and 100 mA·cm−2 at overpotentials of 105 and 226 mV, respectively, in a 1 M phosphate buffer solution (pH = 6.5) with a Tafel slope of 100 mV·dec−1; the currents were stable for over 110 h without obvious decay. Our results suggest that the 3D porous CNT electrode supports could serve as a general platform for earth-abundant HER catalysts for the development of highly efficient electrodes for hydrogen production.
Co-reporter:Guoke Zhao;Xinming Li;Meirong Huang;Zhen Zhen;Yujia Zhong;Qiao Chen;Xuanliang Zhao;Yijia He;Ruirui Hu;Tingting Yang;Rujing Zhang;Changli Li;Jing Kong;Jian-Bin Xu;Rodney S. Ruoff
Chemical Society Reviews 2017 vol. 46(Issue 15) pp:4417-4449
Publication Date(Web):2017/07/31
DOI:10.1039/C7CS00256D
Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major “graphene-on-surface” structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.
Co-reporter:Yujia Zhong, Zhen Zhen, Hongwei Zhu
FlatChem 2017 Volume 4(Volume 4) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.flatc.2017.06.008
•Graphene materials residing at the frontier of scientific research offer immense potential for overcoming the challenges related to the performance, functionality and durability of key functional materials.•This review recollects the latest development in the synthesis, structural analysis, characteristics, and potential applications of graphene materials, to address the continued developments and challenges with a wide scope of interest.•This review highlights fundamental understanding of the synthesis and characterization procedures, future outlook, as well as an in-depth discussion of high-end application areas.Graphene is a representative two-dimensional (2D) material and has been receiving considerable interest from both academia and industry. In this review, we recollect the latest development in the synthesis, structural analysis, characteristics, and possible applications of graphene materials. The discussion helps researchers to better understand the properties of graphene and design novel graphene-based applications.This review highlights the latest development in the synthesis, structural analysis, and properties of graphene materials, with an in-depth discussion of its high-end applications.Download high-res image (96KB)Download full-size image
Co-reporter:Xiaobei Zang, Rujing Zhang, Zhen Zhen, Wenhui Lai, Cheng Yang, Feiyu Kang, Hongwei Zhu
Nano Energy 2017 Volume 40(Volume 40) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.nanoen.2017.08.026
•A flexible and temperature-tolerant supercapacitor is assembled by using hybrid carbon film electrodes and gel electrolyte.•The supercapacitor operates at extreme temperatures (−40~200 °C) with excellent electrochemical properties.•The supercapacitor allows a maximum area specific capacitance of 330 mF/cm2, with 1.7 mWh/cm3 energy density.Flexible supercapacitors have advanced rapidly in recent years and contributed to the development of wearable electronics. However, the operating temperature of the flexible supercapacitors usually falls within a narrow range, because of the constraints of the electrode materials and the electrolytes. Here, we report a flexible supercapacitor that can operate at extreme temperatures (down to −40 °C and up to 200 °C) with excellent electrochemical property and high durability. This device allows a maximum area specific capacitance of 330 mF/cm2. It has 2 F/cm3 volume specific capacitance and 1.7 mWh/cm3 energy density. The high stability of this supercapacitor enables 90% capacitance retention after 105 cycles. Moreover, deformation at extreme temperature does not reduce its energy storage ability.A flexible, temperature-tolerant supercapacitor is designed and fabricated. The electrode materials is carbon hybrid film composed of reduced graphene oxide and carbon nanotube The device works at extreme temperatures (down to −40 °C and up to 200 °C) with excellent electrochemical property and high durability and deformation at extreme temperature without energy storage ability degradation.Download high-res image (183KB)Download full-size image
Co-reporter:Guoke Zhao;Xinming Li;Meirong Huang;Zhen Zhen;Yujia Zhong;Qiao Chen;Xuanliang Zhao;Yijia He;Ruirui Hu;Tingting Yang;Rujing Zhang;Changli Li;Jing Kong;Jian-Bin Xu;Rodney S. Ruoff
Chemical Society Reviews 2017 vol. 46(Issue 23) pp:7469-7469
Publication Date(Web):2017/11/27
DOI:10.1039/C7CS90114C
Correction for ‘The physics and chemistry of graphene-on-surfaces’ by Guoke Zhao, Xinming Li, Meirong Huang et al., Chem. Soc. Rev., 2017, 46, 4417–4449.
Co-reporter:Tingting Yang, Dan Xie, Zhihong Li, Hongwei Zhu
Materials Science and Engineering: R: Reports 2017 Volume 115(Volume 115) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.mser.2017.02.001
Tactile sensors, most commonly referred as strain and pressure sensors, can collect mechanical property data of the human body and local environment, to provide valuable insights into the human health status or artificial intelligence systems. The introduction of a high level of wearability (bendability and stretchability) to tactile sensors can dramatically enhance their interfaces with the contact objects, providing chronically reliable functions. Therefore, the developed wearable tactile sensors are capable of conformably covering arbitrary curved surface over their stiff counterparts without incurring damage, emerging as a promising development direction toward the Internet of Things (IoT) applications. Fundamental parameters of the wearable tactile sensors such as sensitivity and stretchability have experienced unprecedented advancement, owing to the progress of device fabrication techniques and material structural engineering. Moreover, novel smart materials and mechanically durable sensor design concepts endow these sensors with multi-functionality integration (e.g., simultaneous force, temperature and humidity detection, simultaneous pressure and strain discrimination) and stirring properties (e.g., biocompatibility, biodegradability, self-healing, self-powering and visualization), further broadening the application scope of current wearable tactile sensors. Besides, it is desirable that a tactile sensor is compatible with a printing process that presents a new era of feasible wearable technology due to its large-area and high-throughput production capability. In addition to the development of sensors, packaging, and integration of the rest of the tactile device system (data memory, signal conversion, power supply, wireless transmission, feedback actuator, etc.) to build a wearable platform also emerge as major research frontiers in recent years. This review attempts to summarize the current state-of-the-art wearable tactile sensors concerning basic concepts, functional materials, sensing mechanism, promising applications, performance optimization strategies, multifunctional sensing, and system integration. Finally, the discussion will be presented regarding potential challenges, pathways, and opportunities.
Co-reporter:Ruirui Hu;Yijia He;Cuimiao Zhang;Rujing Zhang;Jing Li
Journal of Materials Chemistry A 2017 vol. 5(Issue 48) pp:25632-25640
Publication Date(Web):2017/12/12
DOI:10.1039/C7TA08635K
Herein, a graphene oxide (GO)-modified piperazine (PIP) nanofiltration (NF) membrane was successfully fabricated via in situ interfacial polymerization of PIP-GO and trimesoyl chloride on a porous substrate, in which GO induced a wrinkled membrane surface with improved roughness and hydrophilicity and reduced electronegativity. Ion separation tests show that GO increases the water flux of the membranes significantly by 10–15 LMH for all the studied salt solutions. Furthermore, GO can selectively increase the retention of CaCl2 and MgCl2, but slightly decrease the rejection of MgSO4, NaCl, and KCl; this indicates an improvement in the separation performance of the PIP-GO membrane between divalent and monovalent cations with a common counter ion, Cl−. The enhanced water permeation of the PIP-GO membrane can be ascribed to its increased surface area, hydrophilicity, and ultrafast water transport between GO nanosheets. The GO-promoted selective ion separation is the result of an attenuated electrostatic attraction between Ca2+, Mg2+, and the membrane as well as the water flow-accelerated transport of Na+ and K+. Therefore, GO-modified NF membranes exhibit great potential for applications in the areas of water purification and separation.
Co-reporter:Pengzhan Sun;Kunlin Wang
Advanced Materials 2016 Volume 28( Issue 12) pp:2287-2310
Publication Date(Web):
DOI:10.1002/adma.201502595
Significant achievements have been made on the development of next-generation filtration and separation membranes using graphene materials, as graphene-based membranes can afford numerous novel mass-transport properties that are not possible in state-of-art commercial membranes, making them promising in areas such as membrane separation, water desalination, proton conductors, energy storage and conversion, etc. The latest developments on understanding mass transport through graphene-based membranes, including perfect graphene lattice, nanoporous graphene and graphene oxide membranes are reviewed here in relation to their potential applications. A summary and outlook is further provided on the opportunities and challenges in this arising field. The aspects discussed may enable researchers to better understand the mass-transport mechanism and to optimize the synthesis of graphene-based membranes toward large-scale production for a wide range of applications.
Co-reporter:Xinming Li;Tingting Yang;Yao Yang;Jia Zhu;Li Li;Fakhr E. Alam;Xiao Li;Kunlin Wang;Huanyu Cheng;Cheng-Te Lin;Ying Fang
Advanced Functional Materials 2016 Volume 26( Issue 9) pp:1322-1329
Publication Date(Web):
DOI:10.1002/adfm.201504717
Promoted by the demand for wearable devices, graphene has been proved to be a promising material for potential applications in flexible and highly sensitive strain sensors. However, low sensitivity and complex processing of graphene retard the development toward the practical applications. Here, an environment-friendly and cost-effective method to fabricate large-area ultrathin graphene films is proposed for highly sensitive flexible strain sensor. The assembled graphene films are derived rapidly at the liquid/air interface by Marangoni effect and the area can be scaled up. These graphene-based strain sensors exhibit extremely high sensitivity with gauge factor of 1037 at 2% strain, which represents the highest value for graphene platelets at this small deformation so far. This simple fabrication for strain sensors with highly sensitive performance of strain sensor makes it a novel approach to applications in electronic skin, wearable sensors, and health monitoring platforms.
Co-reporter:Jidong Shi;Xinming Li;Huanyu Cheng;Zhuangjian Liu;Lingyu Zhao;Tingting Yang;Zhaohe Dai;Zengguang Cheng;Enzheng Shi;Long Yang;Zhong Zhang;Anyuan Cao;Ying Fang
Advanced Functional Materials 2016 Volume 26( Issue 13) pp:2078-2084
Publication Date(Web):
DOI:10.1002/adfm.201504804
Transparent, stretchable films of carbon nanotubes (CNTs) have attracted significant attention for applications in flexible electronics, while the lack of structural strength in CNT networks leads to deformation and failure under high mechanical load. In this work, enhancement of the strength and load transfer capabilities of CNT networks by chemical vapor deposition of graphene in the nanotube voids is proposed. The graphene hybridization significantly strengthens the CNT networks, especially at nanotube joints, and enhances their resistance to buckling and bundling under large cyclic strain up to 20%. The hybridized films show linear and reproducible responses to tensile strains, which have been applied in strain sensors to detect human motions with fast response, high sensitivity, and durability.
Co-reporter:Tingting Yang, Xinming Li, Xin Jiang, Shuyuan Lin, Junchao Lao, Jidong Shi, Zhen Zhen, Zhihong Li and Hongwei Zhu
Materials Horizons 2016 vol. 3(Issue 3) pp:248-255
Publication Date(Web):26 Feb 2016
DOI:10.1039/C6MH00027D
This work demonstrates that engineering of the connection channels in gold thin films is an effective way to alter its resistivity for improved sensitivity in strain sensors. We investigated the formation of channel cracks and explored the corresponding piezoresistive behavior. The developed strain sensor possessed GFs as high as 200 (ε < 0.5%), 1000 (0.5% < ε < 0.7%), and even greater than 5000 (0.7% < ε < 1%), which are among the highest values reported thus far at such small deformation, and are promising in the applications of electronic skin, wearable sensors and health monitoring platforms.
Co-reporter:Pengzhan Sun, Renzhi Ma, Wei Ma, Jinghua Wu, Kunlin Wang, Takayoshi Sasaki and Hongwei Zhu
NPG Asia Materials 2016 8(4) pp:e259
Publication Date(Web):2016-04-01
DOI:10.1038/am.2016.38
The development of graphene-based functional membranes with the ability to effectively filter and separate molecules or ions in solutions based on a simple criterion (for example, the size or charge of solutes) is crucial for various engineering-relevant applications, ranging from wastewater purification and reuse to chemical refinement. Here, we report a hybrid membrane consisting of anionic graphene oxide (GO) and cationic Co-Al (or Mg-Al) layered double hydroxide (LDH) nanosheet (NS) superlattice units for high selectivity charge-guided ion transport. The hybrid membrane possesses a series of characteristics, including being easy to access, mechanically robust, freestanding, flexible and semitransparent as well as having a large area. The interlayer spacing of the hybrid membrane is insensitive to humidity variations, ensuring the structural stability in solution-based mass transport applications. The concentration gradient-driven ion transmembrane diffusion experiments show that the cations bearing various valences can be effectively separated strictly according to their charges, independent of the cationic and charge-balancing anionic species. The relative selectivity of the hybrid membranes toward monovalent and trivalent cations is as high as 30, which is not achievable by GO multilayer stacks, LDH-NS multilayer stacks or their bulk-stratified membranes, indicating that a synergistic effect originating from the molecular-level heteroassembly of GO and LDH-NS has a dominant role in the high-performance charge-guided ion filtration and separation processes. These excellent properties of GO/LDH-NS hybrid membranes make them promising candidates in diverse applications, ranging from wastewater treatment and reuse and chemical refinement to biomimetic selective ion transport.
Co-reporter:Xiao Li, Li Zhang, Xiaobei Zang, Xinming Li, and Hongwei Zhu
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 17) pp:10866
Publication Date(Web):April 12, 2016
DOI:10.1021/acsami.6b01903
Hydrogen production from water splitting has been considered as an effective and sustainable method to solve future energy related crisis. Molybdenum sulfides (e.g., MoS2) show promising catalytic ability in hydrogen evolution reaction (HER). Combining MoS2 with conductive carbon-based materials has aroused tremendous research interest recently. In this work, a highly efficient multiple-catalyst is developed for HER by decorating Pt nanoparticles (Pt NPs) on MoS2@graphene protected nickel woven fabrics (NiWF) substrate, which comprises the following components: (i) Graphene protected NiWF acts as the underlying substrate, supporting the whole structure; (ii) MoS2 nanoplates serve as a central and essential photosensitive component, forming a heterostructure with graphene simultaneously; and (iii) on the basis of the intrinsic photoluminescence effect of MoS2, together with the photoelectric response at the MoS2/graphene interface, Pt NPs are successfully deposited on the whole structure under illumination. Particularly and foremost, this work emphasizes on discussion and verification of the underlying mechanism for photopromoted electroless Pt NPs deposition. Due to this assembly approach, the usage amount of Pt is controlled at ∼5 wt % (∼0.59 at. %) with respect to the whole catalyst. MoS2@Substrate with Pt NPs deposited under 643 nm illumination, with the synergistic effect of MoS2 active sites and Pt NPs, demonstrates the most superior electrocatalytic performance, with negligible overpotential and low Tafel slope of 39.4 mV/dec.Keywords: graphene; hydrogen evolution reaction; MoS2; photoluminescence; platinum
Co-reporter:Liancheng Wang, Yan Cheng, Zhiqiang Liu, Xiaoyan Yi, Hongwei Zhu, and Guohong Wang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 2) pp:1176
Publication Date(Web):December 23, 2015
DOI:10.1021/acsami.5b09419
Graphene transparent conductive electrode (TCE) applications in nitride light emitting diodes (LEDs) are still limited by the large contact resistance and interface barrier between graphene and p-GaN. We propose a hybrid tunnel junction (TJ)–graphene TCE approach for nitride lateral LEDs theoretically and experimentally. Through simulation using commercial advanced physical models of semiconductor devices (APSYS), we found that low tunnel resistance can be achieved in the n+-GaN/u-InGaN/p+-GaN TJ, which has a lower tunneling barrier and an enhanced electric field due to the polarization effect. Graphene TCEs and hybrid graphene–TJ TCEs are then modeled. The designed hybrid TJ–graphene TCEs show sufficient current diffusion length (Ls), low introduced series resistance, and high transmittance. The assembled TJ LED with the triple-layer graphene (TLG) TCEs show comparable optoelectrical performance (3.99 V@20 mA, LOP = 10.8 mW) with the reference LED with ITO TCEs (3.36 V@20 mA, LOP = 12.6 mW). The experimental results further prove that the TJ–graphene structure can be successfully incorporated as TCEs for lateral nitride LEDs.Keywords: current spreading; gallium nitride; graphene; light emitting diodes; transparent conductive electrodes; tunnel junction
Co-reporter:Qiao Chen, Shujie Xiao, Rujing Zhang, Fengmei Guo, Kunlin Wang, Hongwei Zhu
Carbon 2016 Volume 103() pp:346-351
Publication Date(Web):July 2016
DOI:10.1016/j.carbon.2016.03.028
A spindle-like hierarchical carbon structure of submicron dimensions is synthesized by floating catalytic deposition using a polyhydroxyalkanoate (PHA)/ferrocene/chloroform precursor. The electron microscopic morphology characterizations demonstrate that as-prepared carbon micro-spindle (CMS) comprises three components: two symmetric carbon cones formed by curved graphitic filaments consisted of randomly orientated graphene layers, and one middle catalyst plate with a rough surface. CMSs only grow on large catalyst plates with complicated surface microstructures. Chlorine is employed to tune the crystallinity of the catalyst, leading to a rough surface of the catalyst plate. Graphene layers are deposited parallel to the catalyst surface. Carbon spindles sharing the same catalyst plate form CMS clusters. The electrochemical performance of CMSs is further investigated, showing good capacitance properties with excellent cycling stability, indicating its application potential in energy storage devices.
Co-reporter:Xin Jiang, Rujing Zhang, Tingting Yang, Shuyuan Lin, Qiao Chen, Zhen Zhen, Dan Xie, Hongwei Zhu
Surface and Coatings Technology 2016 Volume 299() pp:22-28
Publication Date(Web):15 August 2016
DOI:10.1016/j.surfcoat.2016.04.066
•The conductive ink is modified by ionic cellulose ethers•Foldable and electrically stable film resistors are fabricated with graphene conductive ink•Ionic cellulose ethers have positive effect on the contact state of graphene layersFlexible electronics have shown great application potential in mobile telemedicine, man-machine interaction system, and smart robotics. As a key electronic element, resistor's electrical properties should remain stable over their bending range of operation. Here, a shortcut fabrication strategy, vacuum filtration and cutting, to construct foldable and electrically stable graphene-based film resistors are demonstrated. Through investigation of resistor behavior under different stress conditions, it is found that micro-cracks appeared on the surface are correlated to curvature and percolation theories. The effects of ionic cellulose ethers on the contact state of graphene layers under tension and bending are investigated, which efficiently prevent surface crack from happening. This rapid fabrication method to carry out individual customization may further realize other environmental friendly, portable and multifunctional devices.
Co-reporter:Li Zhang, Yanbo Li, Xiao Li, Changli Li, Rujing Zhang, Jean-Jacques Delaunay, Hongwei Zhu
Nano Energy 2016 Volume 28() pp:135-142
Publication Date(Web):October 2016
DOI:10.1016/j.nanoen.2016.08.036
•An earth-abundant CuSbS2 thin film photocathode for hydrogen evolution is demonstrated for the first time.•The prepared CuSbS2 thin film is homogenous over large area and exhibits desirable large columnar grains.•The PEC performance is comparable to the state-of-the-art Cu2ZnSnS4 and Cu2O photocathodes.Cost-effective photoelectrochemical water splitting requires highly efficient and inexpensive electrode materials. Herein, we report a novel earth-abundant photocathode for hydrogen evolution consisting of a CdS-modified CuSbS2 synthesized using low-cost and high-throughput solution processes. The prepared CuSbS2 thin film is homogenous over large area and exhibits desirable micrometer-sized columnar grain structure. The fabricated CuSbS2/CdS/Pt photocathode achieves a cathodic photocurrent of −4.2 mA cm−2 at 0 VRHE, an onset potential of 0.46 VRHE, and a stable cathodic photocurrent with nearly unity of Faraday efficiency for hydrogen production in neutral electrolyte under AM 1.5 G simulated sunlight illumination. In addition, the CuSbS2-based photocathode possesses a significant response to visible light with an optical absorption edge around 860 nm, so that the reported CuSbS2 photocathode offers potential for efficient use of solar radiation without resorting to expensive raw materials and fabrication techniques.We report for the first time that solution-processed CuSbS2 thin film coupled with thin CdS layer to form p-n heterojunction could serve as a viable earth-abundant photocathode for hydrogen evolution.
Co-reporter:Xinming Li;Zheng Lv
Advanced Materials 2015 Volume 27( Issue 42) pp:6549-6574
Publication Date(Web):
DOI:10.1002/adma.201502999
In the last few decades, advances and breakthroughs of carbon materials have been witnessed in both scientific fundamentals and potential applications. The combination of carbon materials with traditional silicon semiconductors to fabricate solar cells has been a promising field of carbon science. The power conversion efficiency has reached 15–17% with an astonishing speed, and the diversity of systems stimulates interest in further research. Here, the historical development and state-of-the-art carbon/silicon heterojunction solar cells are covered. Firstly, the basic concept and mechanism of carbon/silicon solar cells are introduced with a specific focus on solar cells assembled with carbon nanotubes and graphene due to their unique structures and properties. Then, several key technologies with special electrical and optical designs are introduced to improve the cell performance, such as chemical doping, interface passivation, anti-reflection coatings, and textured surfaces. Finally, potential pathways and opportunities based on the carbon/silicon heterojunction are envisaged. The aspects discussed here may enable researchers to better understand the photovoltaic effect of carbon/silicon heterojunctions and to optimize the design of graphene-based photodevices for a wide range of applications.
Co-reporter:Pengzhan Sun, Qiao Chen, Xinda Li, He Liu, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu, Renzhi Ma, Takayoshi Sasaki and Hongwei Zhu
NPG Asia Materials 2015 7(2) pp:e162
Publication Date(Web):2015-02-01
DOI:10.1038/am.2015.7
By intercalating monolayer titania (TO) nanosheets into graphene oxide (GO) laminates with mild ultraviolet (UV) reduction, the as-prepared RGO/TO hybrid membranes exhibit excellent water desalination performances. Without external hydrostatic pressures, the ion permeations through the RGO/TO hybrid membranes can be reduced to <5% compared with the GO/TO cases, while the water transmembrane permeations, which are measured using an isotope-labeling technique, can be retained up to ~60%. The mechanism for the excellent water desalination performances of the RGO/TO hybrid laminates is discussed, which indicates that the photoreduction of GO by TO is responsible for the effective rejection of ions, while the photoinduced hydrophilic conversion of TO under UV irradiation is responsible for the well-retained water permeabilities. These excellent properties make RGO/TO hybrid membranes favorable for practical water desalination.
Co-reporter:Miao Zhu, Li Zhang, Xinming Li, Yijia He, Xiao Li, Fengmei Guo, Xiaobei Zang, Kunlin Wang, Dan Xie, Xuanhua Li, Bingqing Wei and Hongwei Zhu
Journal of Materials Chemistry A 2015 vol. 3(Issue 15) pp:8133-8138
Publication Date(Web):11 Mar 2015
DOI:10.1039/C5TA00702J
Graphene/Si has been proved to form a quality Schottky junction with high photoelectric conversion efficiency at AM 1.5. However, for the ultraviolet portion of the incident light, the photoelectric performance will degrade significantly due to severe absorption and recombination at the front surface. Herein, to realize enhanced ultraviolet detection with a graphene/Si diode, TiO2 nanoparticles (NPs, 3–5 nm) are synthesized and spin-coated on the graphene surface to improve the photoresponse in the ultraviolet region. According to our results, the conversion efficiency of the graphene/Si diode at 420 nm and 350 nm increases by 72.7% and 100% respectively with TiO2 coating. Then C−2–V measurements of both TiO2 and graphene/Si diode are performed to analyze the electronic band structure of the TiO2/graphene/Si system, based on which we finally present the enhancement mechanism of photodetection using TiO2 NPs.
Co-reporter:Xiao Li, Xinming Li, Xiaobei Zang, Miao Zhu, Yijia He, Kunlin Wang, Dan Xie and Hongwei Zhu
Nanoscale 2015 vol. 7(Issue 18) pp:8398-8404
Publication Date(Web):01 Apr 2015
DOI:10.1039/C5NR00904A
Hydrogen plays a crucial role in the chemical vapor deposition (CVD) growth of graphene. Here, we have revealed the roles of hydrogen in the two-step CVD growth of MoS2. Our study demonstrates that hydrogen acts as the following: (i) an inhibitor of the thermal-induced etching effect in the continuous film growth process; and (ii) a promoter of the desulfurization reaction by decreasing the S/Mo atomic ratio and the oxidation reaction of the obtained MoSx (0 < x < 2) films. A high hydrogen content of more than 100% in argon forms nano-sized circle-like defects and damages the continuity and uniformity of the film. Continuous MoS2 films with a high crystallinity and a nearly perfect S/Mo atomic ratio were finally obtained after sulfurization annealing with a hydrogen content in the range of 20%–80%. This insightful understanding reveals the crucial roles of hydrogen in the CVD growth of MoS2 and paves the way for the controllable synthesis of two-dimensional materials.
Co-reporter:Xiaobei Zang, Xiao Li, Miao Zhu, Xinming Li, Zhen Zhen, Yijia He, Kunlin Wang, Jinquan Wei, Feiyu Kang and Hongwei Zhu
Nanoscale 2015 vol. 7(Issue 16) pp:7318-7322
Publication Date(Web):16 Mar 2015
DOI:10.1039/C5NR00584A
We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm−2, and exhibit excellent cycling stability with ∼100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.
Co-reporter:Pengzhan Sun, He Liu, Kunlin Wang, Minlin Zhong, Dehai Wu and Hongwei Zhu
Chemical Communications 2015 vol. 51(Issue 15) pp:3251-3254
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4CC10103K
Based on isotope labelling, we found that liquid water can afford an ultrafast permeation through graphene-based nanochannels with a diffusion coefficient 4–5 orders of magnitude greater than in the bulk case. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is slightly faster than water, indicating that the ions are mainly transported by water flows and the delicate interactions between ions and nanocapillary walls also take effect in the accelerated ion transportation.
Co-reporter:Rujing Zhang, Qiao Chen, Zhen Zhen, Xin Jiang, Minlin Zhong, and Hongwei Zhu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 34) pp:19145
Publication Date(Web):August 18, 2015
DOI:10.1021/acsami.5b04808
Assembling particular building blocks into composites with diverse targeted structures has attracted considerable interest for understanding its new properties and expanding the potential applications. Anisotropic organization is considered as a frequently used targeted architecture and possesses many peculiar properties because of its unusual shapes. Here, we show that anisotropic graphene monoliths (AGMs), three-dimensional architectures of well-aligned graphene sheets obtained by a dip-coating method using cellulose acetate fibers as templates show thermal-insulating, fire-retardant, and anisotropic properties. They exhibit a feature of higher mechanical strength and thermal/electrical conductivities in the axial direction than in the radial direction. Elastic polymer resins are then introduced into the pores of the AGMs to form conductive and flexible composites. The composites, as AGMs, retain the unique anisotropic properties, revealing opposite resistance change under compressions in different directions. The outstanding anisotropic properties of AGMs make them possible to be applied in the fields of thermal insulation, integrated circuits, and electromechanical devices.Keywords: anisotropic; composite; graphene; monolith; multifunctional
Co-reporter:Miao Zhu, Xinming Li, Sunki Chung, Liyun Zhao, Xiao Li, Xiaobei Zang, Kunlin Wang, Jinquan Wei, Minlin Zhong, Kun Zhou, Dan Xie, Hongwei Zhu
Carbon 2015 Volume 84() pp:138-145
Publication Date(Web):April 2015
DOI:10.1016/j.carbon.2014.12.008
Reduced graphene oxide (RGO)/Si Schottky diode has been fabricated by a simple drop-casting/annealing process. Common combustible and/or toxic gases including CH4, O2, CO, NO2, NO, and SO2 were employed to evaluate the detection performance of such device. The relationship between current response and gas flow rate, concentration, bias voltage as well as operating time has been systematically studied, and the results indicated that the RGO/Si-based device is selective to gases like NO2 and NO. In some cases (i.e. flow rate detection), however, the current response for one gas is completely contrary to others, presumably due to the oxygen functional groups (OFGs) presiding on the surface of reduced graphene oxide. Finally, the effects of OFGs on the gas detection performance of RGO/Si-based devices were thoroughly discussed.
Co-reporter:Yangyang Zhang, Zhen Zhen, Zelin Zhang, Junchao Lao, Jinquan Wei, Kunlin Wang, Feiyu Kang, Hongwei Zhu
Electrochimica Acta 2015 Volume 157() pp:134-141
Publication Date(Web):1 March 2015
DOI:10.1016/j.electacta.2015.01.084
•Carbon nanotube/graphene (CNT/G) composite sponges are synthesized by a simple, in-situ unzipping method.•Polypyrrole is electro-polymerized onto the sponge to form CNT/G/polypyrrole (CNT/G/PPy) composite sponge.•The specific capacitance is improved from 4 to 225 F/g for the CNT/G/PPy composite.•The CNT/G/PPy sponge retains the internal conductive network and exhibits excellent capacitive performance.Carbon nanotube/graphene (CNT/G) composite sponge is prepared by in-situ partially unzipping of CNT sponge. Polypyrrole is then electro-polymerized onto the sponge to form CNT/graphene/polypyrrole (CNT/G/PPy) ternary composite sponge. The capacitive behavior of the composite is investigated by using cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The results show that the degree of unzipping of CNT can be controlled by regulating the period of reaction. The specific capacitance of CNT/G sponge shows a significant improvement compared to that of the original CNT sponge (from 4 to 103 F/g). With PPy coating, the CNT/G/PPy displays a high specific capacitance of 225 F/g and excellent capacitance retention of 90.6% after 1000 cycles. In addition, the CNT/G/PPy sponge shows a high capacitance performance under compression. This work indicates that it is possible to build high performance compressive electrodes using CNT/G core networks coated with conductive polymer.
Co-reporter:Tingting Yang, Wen Wang, Hongze Zhang, Xinming Li, Jidong Shi, Yijia He, Quan-shui Zheng, Zhihong Li, and Hongwei Zhu
ACS Nano 2015 Volume 9(Issue 11) pp:10867
Publication Date(Web):October 15, 2015
DOI:10.1021/acsnano.5b03851
Nanomaterials serve as promising candidates for strain sensing due to unique electromechanical properties by appropriately assembling and tailoring their configurations. Through the crisscross interlacing of graphene microribbons in an over-and-under fashion, the obtained graphene woven fabric (GWF) indicates a good trade-off between sensitivity and stretchability compared with those in previous studies. In this work, the function of woven fabrics for highly sensitive strain sensing is investigated, although network configuration is always a strategy to retain resistance stability. The experimental and simulation results indicate that the ultrahigh mechanosensitivity with gauge factors of 500 under 2% strain is attributed to the macro-woven-fabric geometrical conformation of graphene, which induces a large interfacial resistance between the interlaced ribbons and the formation of microscale-controllable, locally oriented zigzag cracks near the crossover location, both of which have a synergistic effect on improving sensitivity. Meanwhile, the stretchability of the GWF could be tailored to as high as over 40% strain by adjusting graphene growth parameters and adopting oblique angle direction stretching simultaneously. We also demonstrate that sensors based on GWFs are applicable to human motion detection, sound signal acquisition, and spatially resolved monitoring of external stress distribution.Keywords: crack; e-skin; graphene; interface; strain sensor; woven fabrics;
Co-reporter:Yan Wang;Tingting Yang;Junchao Lao;Rujing Zhang;Yangyang Zhang
Nano Research 2015 Volume 8( Issue 5) pp:1627-1636
Publication Date(Web):2015 May
DOI:10.1007/s12274-014-0652-3
A wearable and high-precision sensor for sound signal acquisition and recognition was fabricated from thin films of specially designed graphene woven fabrics (GWFs). Upon being stretched, a high density of random cracks appears in the network, which decreases the current pathways, thereby increasing the resistance. Therefore, the film could act as a strain sensor on the human throat in order to measure one’s speech through muscle movement, regardless of whether or not a sound is produced. The ultra-high sensitivity allows for the realization of rapid and low-frequency speech sampling by extracting the signature characteristics of sound waves. In this study, representative signals of 26 English letters, typical Chinese characters and tones, and even phrases and sentences were tested, revealing obvious and characteristic changes in resistance. Furthermore, resistance changes of the graphene sensor responded perfectly with pre-recorded sounds. By combining artificial intelligence with digital signal processing, we expect that, in the future, this graphene sensor will be able to successfully negotiate complex acoustic systems and large quantities of audio data.
Co-reporter:Xin Jiang, Yachang Cao, Kunlin Wang, Jinquan Wei, Dehai Wu, Hongwei Zhu
Surface and Coatings Technology 2015 Volume 261() pp:327-330
Publication Date(Web):15 January 2015
DOI:10.1016/j.surfcoat.2014.11.008
•We investigate the optical properties of graphene-based antireflective coating.•We combine the anodic etching with cathodic polarization and isotropic etching.•The reflectance of graphene coating at normal incidence is up to 0.002%.•Graphene introduces micro-patterns, edge states and non-uniform in-depth density.Electrochemical anisotropic etching, along with prior cathodic polarization during anodic etching, is used to form homogeneous antireflective (AR) structures on metal surfaces. Further electrophoretic deposition forms graphene oxide (GO) nanostructures. The graphene-based AR coating is achieved by electrochemical reduction of GO. Optical metal surfaces with high efficiency of light absorption and low reflectivity are obtained. Our results demonstrate the potential use of graphene in anti-reflection coating.Electrochemical anisotropic etching, along with prior cathodic polarization during anodic etching, is used to form homogeneous antireflective structures on metal surfaces with an ultralow spectral reflectivity of 0.002%.
Co-reporter:Xiao Li, Hongwei Zhu
Journal of Materiomics 2015 Volume 1(Issue 1) pp:33-44
Publication Date(Web):March 2015
DOI:10.1016/j.jmat.2015.03.003
Graphene-like two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been attracting a wide range of research interests. Molybdenum disulfide (MoS2) is one of the most typical TMDCs. Its particular direct band gap of 1.8 eV in monolayer and layer dependence of band structure tackle the gapless problems of graphene, thus making it scientific and industrial importance. In this Review, we attempt to provide the latest development of optical and electronic properties, synthesis approaches, and potential applications of 2D MoS2. A roadmap towards fabricating hybrid structures based on MoS2 and graphene is highlighted, proposing ways to enhance properties of the individual component and broaden the range of functional applications in various fields, including flexible electronics, energy storage and harvesting as well as electrochemical catalysis.We review the recent advances of synthesis approaches, optical and electronic properties, and potential applications of two-dimensional MoS2Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Junchao Lao;Yijia He;Xiao Li;Fuzhang Wu;Tingting Yang;Miao Zhu
Nano Research 2015 Volume 8( Issue 8) pp:2467-2473
Publication Date(Web):2015 August
DOI:10.1007/s12274-015-0754-6
We report a voltage generator based on a graphene network (GN). In response to the movement of a droplet of ionic solution over a GN strip, a voltage of several hundred millivolts is observed under ambient conditions. In the voltage-generation process, the unique structure of GN plays an important role in improving the rate of electron transfer. Given their excellent mechanical properties, GNs may find applications for harvesting vibrational energy in various places such as raincoats, umbrellas, windows, and other surfaces that are exposed to rain.
Co-reporter:Liancheng Wang, Wei Liu, Yiyun Zhang, Zi-Hui Zhang, Swee Tiam Tan, Xiaoyan Yi, Guohong Wang, Xiaowei Sun, Hongwei Zhu, Hilmi Volkan Demir
Nano Energy 2015 Volume 12() pp:419-436
Publication Date(Web):March 2015
DOI:10.1016/j.nanoen.2014.12.035
•Overview of current status for graphene transparent conductive electrodes.•GaN/graphene contact analysis.•Review of graphene transparent conductive electrodes for GaN-based LEDs by interface engineering and chemical doping.•Two approaches proposed: tunnel junction (TJ) and local graphene growth on GaN.Graphene, with attractive electrical, optical, mechanical and thermal properties, is considered to be an ideal candidate for transparent conductive electrodes (TCEs) in many optoelectronic devices, including III-nitride based devices. However, high contact resistivity (ρc) between graphene and GaN (especially p-GaN) has become a major challenge for graphene TCEs utilization in GaN-based light-emitting diodes (LEDs). Here, we analyzed the graphene/GaN contact junction in detail and reviewed the current research progress for reducing ρc in graphene TCEs on GaN LEDs, including interface engineering, chemical doping and tunnel junction design. We also analyzed the current diffusion length for a single layer graphene (SLG) and multiple layer graphene (MLG) TCEs. Finally, to improve the fabrication process compatibility and simplicity with paramount reproduction, a method of directly growing graphene films on GaN by chemical vapor deposition (CVD) is proposed. We also give a short analysis on the reliability of graphene TCEs for GaN-based LEDs. It is believed that this is the ultimate solution for graphene TCEs application for GaN-based LEDs and others in general for other opto- and electrical devices.We review the graphene transparent conductive electrodes for GaN-based light emitting diodes and propose here the tunneling junction combined local graphene growth approach.
Co-reporter:Xin Jiang, Yachang Cao, Peixu Li, Jinquan Wei, Kunlin Wang, Dehai Wu, Hongwei Zhu
Materials Letters 2015 140() pp: 43-47
Publication Date(Web):
DOI:10.1016/j.matlet.2014.10.162
Co-reporter:Xiao Li;Xiaobei Zang;Xinming Li;Miao Zhu;Qiao Chen;Kunlin Wang;Minlin Zhong;Jinquan Wei;Dehai Wu
Advanced Energy Materials 2014 Volume 4( Issue 14) pp:
Publication Date(Web):
DOI:10.1002/aenm.201400224
A hybrid heterojunction and solid-state photoelectrochemical solar cell based on graphene woven fabrics (GWFs) and silicon is designed and fabricated. The GWFs are transferred onto n-Si to form a Schottky junction with an embedded polyvinyl alcohol based solid electrolyte. In the hybrid solar cell, solid electrolyte serves three purposes simutaneously; it is an anti-reflection layer, a chemical modification carrier, and a photoelectrochemical channel. The open-circuit voltage, short-circuit current density, and fill factor are all significantly improved, achieving an impressive power conversion efficiency of 11%. Solar cell models are constructed to confirm the hybrid working mechanism, with the heterojunction junction and photoelectrochemical effect functioning synergistically.
Co-reporter:Yan Wang;Li Wang;Tingting Yang;Xiao Li;Xiaobei Zang;Miao Zhu;Kunlin Wang;Dehai Wu
Advanced Functional Materials 2014 Volume 24( Issue 29) pp:4666-4670
Publication Date(Web):
DOI:10.1002/adfm.201400379
Sensing strain of soft materials in small scale has attracted increasing attention. In this work, graphene woven fabrics (GWFs) are explored for highly sensitive sensing. A flexible and wearable strain sensor is assembled by adhering the GWFs on polymer and medical tape composite film. The sensor exhibits the following features: ultra-light, relatively good sensitivity, high reversibility, superior physical robustness, easy fabrication, ease to follow human skin deformation, and so on. Some weak human motions are chosen to test the notable resistance change, including hand clenching, phonation, expression change, blink, breath, and pulse. Because of the distinctive features of high sensitivity and reversible extensibility, the GWFs based piezoresistive sensors have wide potential applications in fields of the displays, robotics, fatigue detection, body monitoring, and so forth.
Co-reporter:Pengzhan Sun, Kunlin Wang, Jinquan Wei, Minlin Zhong, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2014 vol. 2(Issue 21) pp:7734-7737
Publication Date(Web):31 Mar 2014
DOI:10.1039/C4TA00668B
The efficient recovery of acids from iron-based electrolytes using graphene oxide (GO) membranes was demonstrated for the first time. The results revealed that the amount of H+ permeating the GO membranes and reaching drains was two orders of magnitude larger than that of Fe3+. Notably, when the FeCl3 source concentration was reduced to certain extent, Fe3+ could be completely blocked by GO membranes. The mechanism for the effective separation of H+ from Fe3+ was studied, suggesting that the molecular sieving effect of GO nanocapillaries and the coordination between Fe3+ and GO were responsible for the effective blockage of Fe3+ while the rapid propagation of H+ through hydrogen-bonding networks along water layers within the interlayer spacing was responsible for the fast migration of H+. These properties made GO membranes promising cation-exchange membranes for applications of wastewater reuse and membrane separation.
Co-reporter:Lili Fan, Kunlin Wang, Jinquan Wei, Minlin Zhong, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2014 vol. 2(Issue 32) pp:13123-13128
Publication Date(Web):13 Jun 2014
DOI:10.1039/C4TA01975J
Nanoparticles are ubiquitously existent on the surface of graphene films prepared by chemical vapour deposition. However, studies that thoroughly explore this phenomenon are still fairly limited. In this work, we have demonstrated that the location of nanoparticles should be a straightforward reflection of the nucleation sites of graphene growth. In addition, the deposition of nanoparticles is consistent with the distribution of multilayer graphene. We have found that nanoparticles are not nucleation seeds as proposed by other groups; instead, they are sediment-like materials similar to the graphene films prepared on copper substrates.
Co-reporter:Miao Zhu, Xinming Li, Yibo Guo, Xiao Li, Pengzhan Sun, Xiaobei Zang, Kunlin Wang, Minlin Zhong, Dehai Wu and Hongwei Zhu
Nanoscale 2014 vol. 6(Issue 9) pp:4909-4914
Publication Date(Web):25 Feb 2014
DOI:10.1039/C4NR00056K
Reduced graphene oxide (RGO) has been employed as an electrode for a series of vertically structured photodetectors. Compared with mechanically exfoliated or chemical vapor deposited graphene, RGO possesses more oxygen containing groups and defects, which are proved to be favorable to enhance the performance of photodetectors. As a matter of fact, RGO with different reduction levels can be readily obtained by varying the annealing temperature. The synthesis procedures for the RGO material are suitable for large scale production and its performance can be effectively improved by functionalization or element doping. For RGO-based devices, the Schottky junction properties and photoelectric conversion have been investigated, primarily by analyzing their current–voltage characteristics. Subsequently, the ON/OFF ratio, responsivity and detectivity of the photodetectors were closely examined, proving that the RGO material could be effectively utilized as the electrode material; also, their relationship with the RGO reduction levels has also been explored. By analyzing the response/recovery speed of the RGO-based photodetectors, we have studied the effects of oxygen-containing functional groups and crystalline defects on the photoelectric conversion.
Co-reporter:Ning Wei, Cheng Chang, Hongwei Zhu and Zhiping Xu
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 22) pp:10295-10300
Publication Date(Web):10 Feb 2014
DOI:10.1039/C3CP55063J
Monatomic metal (e.g. silver) structures could form preferably at graphene edges. We explore their structural and electronic properties by performing density functional theory based first-principles calculations. The results show that cohesion between metal atoms, as well as electronic coupling between metal atoms and graphene edges offer remarkable structural stability of the hybrid. We find that the outstanding mechanical properties of graphene allow tunable properties of the metal monatomic structures by straining the structure. The concept is extended to metal rings and helices that form at open ends of carbon nanotubes and edges of twisted graphene ribbons. These findings demonstrate the role of graphene edges as an efficient one-dimensional template for low-dimensional metal structures that are mechanotunable.
Co-reporter:Qiao Chen, Xinming Li, Xiaobei Zang, Yachang Cao, Yijia He, Peixu Li, Kunlin Wang, Jinquan Wei, Dehai Wu and Hongwei Zhu
RSC Advances 2014 vol. 4(Issue 68) pp:36253-36256
Publication Date(Web):04 Aug 2014
DOI:10.1039/C4RA05553E
A solid-state supercapacitor with a flexible, simple structure based on graphene thin film electrodes and acid/base/salt–PVA gel electrolytes is reported. The performance of six different gel electrolytes (H3PO4, H2SO4, KOH, NaOH, KCl, NaCl) in this graphene-based supercapacitor are investigated. The electrochemical properties of this highly flexible, stable supercapacitor are enhanced by optimizing the concentration of the electrolyte in polymer gel.
Co-reporter:Miao Zhu;Xinming Li;Zexia Zhang;Pengzhan Sun;Xiaobei Zang;Kunlin Wang;Minlin Zhong;Dehai Wu
Advanced Engineering Materials 2014 Volume 16( Issue 5) pp:532-538
Publication Date(Web):
DOI:10.1002/adem.201300408
Co-reporter:Rujing Zhang;Yachang Cao;Peixu Li;Xiaobei Zang;Pengzhan Sun
Nano Research 2014 Volume 7( Issue 10) pp:1477-1487
Publication Date(Web):2014 October
DOI:10.1007/s12274-014-0508-x
With the combination of surfactant and freeze-drying, we have developed two kinds of graphene spongy structures. On the one hand, using foams of soap bubbles as templates, three-dimensional porous graphene sponges with rich hierarchical pores have been synthesized. Pores of the material contain three levels of length scales, including millimeter, micrometer and nanometer. The structure can be tuned by changing the freezing media, adjusting the stirring rate or adding functional additives. On the other hand, by direct freeze-drying of a graphene oxide/surfactant suspension, a porous framework with directionally aligned pores is prepared. The surfactant gives a better dispersion of graphene oxide sheets, resulting in a high specific surface area. Both of the obtained materials exhibit excellent absorption capacity and good compression performance, providing a broad range of possible applications, such as absorbents, storage media, and carriers.
Co-reporter:Pengzhan Sun, Feng Zheng, Miao Zhu, Zhigong Song, Kunlin Wang, Minlin Zhong, Dehai Wu, Reginald B. Little, Zhiping Xu, and Hongwei Zhu
ACS Nano 2014 Volume 8(Issue 1) pp:850
Publication Date(Web):January 8, 2014
DOI:10.1021/nn4055682
Graphene and graphene oxide (G–O) have been demonstrated to be excellent filters for various gases and liquids, showing potential applications in areas such as molecular sieving and water desalination. In this paper, the selective trans-membrane transport properties of alkali and alkaline earth cations through a membrane composed of stacked and overlapped G–O sheets (“G–O membrane”) are investigated. The thermodynamics of the ion transport process reveal that the competition between the generated thermal motions and the interactions of cations with the G–O sheets results in the different penetration behaviors to temperature variations for the considered cations (K+, Mg2+, Ca2+, and Ba2+). The interactions between the studied metal atoms and graphene are quantified by first-principles calculations based on the plane-wave-basis-set density functional theory (DFT) approach. The mechanism of the selective ion trans-membrane transportation is discussed further and found to be consistent with the concept of cation−π interactions involved in biological systems. The balance between cation−π interactions of the cations considered with the sp2 clusters of G–O membranes and the desolvation effect of the ions is responsible for the selectivity of G–O membranes toward the penetration of different ions. These results help us better understand the ion transport process through G–O membranes, from which the possibility of modeling the ion transport behavior of cellular membrane using G–O can be discussed further. The selectivity toward different ions also makes G–O membrane a promising candidate in areas of membrane separations.Keywords: alkali and alkaline earth cations; cation−π interaction; first-principles calculations; graphene oxide; selective permeation; thermodynamics
Co-reporter:Pengzhan Sun ; He Liu ; Kunlin Wang ; Minlin Zhong ; Dehai Wu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 33) pp:19396-19401
Publication Date(Web):July 29, 2014
DOI:10.1021/jp504921p
Recently, graphene oxide (GO) membranes have been reported with the ability to separate different solutes in aqueous suspensions by a molecular sieving effect. On the other hand, we propose that the chemical interactions between ions and GO membranes might also take effect in selective ion transmembrane transportation. In this paper, on the basis of the permeation of Cu2+ and Mg2+ sources through hydroxyl-, carboxyl-, and amino-functionalized graphene membranes, the delicate ion–graphene interactions which might be responsible for the selective ion permeation are investigated. We demonstrate experimentally that the coordination between transition-metal cations and carboxyl functionalities and the cation−π interactions between main-group cations and sp2 regions are responsible for the selective transport of small ions through graphene-based membranes, which is beyond the scope of molecular sieving effect proposed previously. Notably, by grafting amino groups onto the graphene basal planes, the permeations of Cu2+ and Mg2+ cations are both weakened. These results not only throw light upon the mechanism for the selective ion permeation through graphene-based membranes but also lay a foundation for the separation of target ions by grafting specific functionalities.
Co-reporter:Liancheng Wang, Jun Ma, Zhiqiang Liu, Xiaoyan Yi, Hongwei Zhu, and Guohong Wang
ACS Photonics 2014 Volume 1(Issue 5) pp:421
Publication Date(Web):April 29, 2014
DOI:10.1021/ph500133w
Gallium-nitride (GaN)-based hexagonal pyramids array vertical light emitting diodes (HPA VLEDs) have been assembled through compatible and rationally designed semiconductor fabrication processes. Compared with regular VLEDs (R-VLEDs), the HPA VLEDs have intrinsic bendability and showed a ∼56% improvement in internal quantum efficiency (IQE) and a ∼52% improvement in light extraction efficiency (LEE). Time-dependent photoluminescence (TDPL) tests and ray tracing simulations confirmed their improved IQE and LEE, respectively. Furthermore, HPA VLEDs with multilayer graphene (MLG) as the electrical interconnects were able to be locally bent and exhibited a stable optical output after many cycles of bending. To obtain uniform microscale HPA, a “dislocation engineering” approach was conceptually demonstrated. The proposed scheme was established for simple materials and low cost engineering; it will guide the fabrication of flexible optoelectronics, especially flexible inorganic GaN-based LEDs.Keywords: dislocation engineering approach; flexible; gallium-nitride (GaN); MOCVD; pattered sapphire substrate; vertical light emitting diodes; wet etching
Co-reporter:Pengzhan Sun;Kunlin Wang;Jinquan Wei;Minlin Zhong;Dehai Wu
Nano Research 2014 Volume 7( Issue 10) pp:1507-1518
Publication Date(Web):2014 October
DOI:10.1007/s12274-014-0512-1
The magnetic transitions in graphene oxide (GO) have been investigated experimentally. Micron-sized GO flakes exhibit dominant diamagnetism accompanied by weak ferromagnetism at room temperature. However, when the lateral dimensions of GO flakes are reduced from micron-size to nano-size, a clear transition from dominant diamagnetism to ferromagnetism is observed. After reducing the GO chemically or thermally, the dominant magnetic properties are not altered markedly except for the gradual enhancement of ferromagnetic components. In contrast, at 2 K, significant paramagnetism is present in both the micron-sized and nano-sized GO sheets. The effects of different functional groups on magnetic transitions in graphene derivatives have been further investigated using on hydroxyl-, carboxyl-, amino- and thiolfunctionalized graphene. The results reveal that significant diamagnetism with weak ferromagnetism is present at room temperature in all of these functionalized graphene derivatives and the ability of different functional groups to introduce magnetic moments follows the order -SH > -OH > -COOH, -NH2. Notably, at 5 K, diamagnetism, paramagnetism and ferromagnetism coexist in thiol-, hydroxyland carboxyl-functionalized graphene, while amino-graphene exhibits dominant paramagnetism, analogous to the low-temperature magnetism in GO. These results indicate that diamagnetism, paramagnetism and ferromagnetism can coexist in graphene derivatives and magnetic transitions among the three states can be achieved which depend on edge states, vacancies, chemical doping and the attached functional groups. The results obtained may help settle the current controversy about the magnetism of graphene-related materials.
Co-reporter:Tingting Yang;Hongze Zhang;Yan Wang;Xiao Li;Kunlin Wang;Jinquan Wei
Nano Research 2014 Volume 7( Issue 6) pp:869-876
Publication Date(Web):2014 June
DOI:10.1007/s12274-014-0448-5
Co-reporter:Yuxuan Lin, Xinming Li, Dan Xie, Tingting Feng, Yu Chen, Rui Song, He Tian, Tianling Ren, Minlin Zhong, Kunlin Wang and Hongwei Zhu
Energy & Environmental Science 2013 vol. 6(Issue 1) pp:108-115
Publication Date(Web):06 Nov 2012
DOI:10.1039/C2EE23538B
Theoretical and experimental studies have been performed to simulate and optimize graphene/semiconductor heterojunction solar cells. By controlling graphene layer number, tuning graphene work function and adding an antireflection film, a maximal theoretical conversion efficiency of ∼9.2% could be achieved. Following the theoretical optimization proposal, the Schottky junction solar cells with modified graphene films and silicon pillar arrays were fabricated and were found to give a conversion efficiency of up to 7.7%.
Co-reporter:Xinming Li;Dan Xie;Hyesung Park;Tingying Helen Zeng;Kunlin Wang;Jinquan Wei;Minlin Zhong;Dehai Wu;Jing Kong
Advanced Energy Materials 2013 Volume 3( Issue 8) pp:1029-1034
Publication Date(Web):
DOI:10.1002/aenm.201300052
Co-reporter:Enzheng Shi, Hongbian Li, Long Yang, Luhui Zhang, Zhen Li, Peixu Li, Yuanyuan Shang, Shiting Wu, Xinming Li, Jinquan Wei, Kunlin Wang, Hongwei Zhu, Dehai Wu, Ying Fang, and Anyuan Cao
Nano Letters 2013 Volume 13(Issue 4) pp:1776-1781
Publication Date(Web):March 21, 2013
DOI:10.1021/nl400353f
Carbon nanotube-Si and graphene-Si solar cells have attracted much interest recently owing to their potential in simplifying manufacturing process and lowering cost compared to Si cells. Until now, the power conversion efficiency of graphene-Si cells remains under 10% and well below that of the nanotube-Si counterpart. Here, we involved a colloidal antireflection coating onto a monolayer graphene-Si solar cell and enhanced the cell efficiency to 14.5% under standard illumination (air mass 1.5, 100 mW/cm2) with a stable antireflection effect over long time. The antireflection treatment was realized by a simple spin-coating process, which significantly increased the short-circuit current density and the incident photon-to-electron conversion efficiency to about 90% across the visible range. Our results demonstrate a great promise in developing high-efficiency graphene-Si solar cells in parallel to the more extensively studied carbon nanotube-Si structures.
Co-reporter:Xiao Li;Xiaobei Zang;Zhen Li;Xinming Li;Peixu Li;Pengzhan Sun;Xiao Lee;Rujing Zhang;Zhenghong Huang;Kunlin Wang;Dehai Wu;Feiyu Kang
Advanced Functional Materials 2013 Volume 23( Issue 38) pp:4862-4869
Publication Date(Web):
DOI:10.1002/adfm.201300464
Abstract
New porous materials are of great importance in many technological applications. Here, the direct synthesis of multi-layer graphene and porous carbon woven composite films by chemical vapor deposition on Ni gauze templates is reported. The composite films integrate the dual advantages of graphene and porous carbon, having not only the excellent electrical properties and flexibility of graphene but also the porous characteristics of amorphous carbon. The multi-layer graphene/porous carbon woven fabric film creates a new platform for a variety of applications, such as fiber supercapacitors. The designed composite film has a capacitance of 20 μF/cm2, which is close to the theoretical value and a device areal capacitance of 44 mF/cm2.
Co-reporter:Xinming Li, Dan Xie, Hyesung Park, Miao Zhu, Tingying Helen Zeng, Kunlin Wang, Jinquan Wei, Dehai Wu, Jing Kong and Hongwei Zhu
Nanoscale 2013 vol. 5(Issue 5) pp:1945-1948
Publication Date(Web):03 Jan 2013
DOI:10.1039/C2NR33795A
We demonstrated the p-type chemical doping by chlorine and nitrate anions to enhance the Schottky junction in the solar cell. Nitrate ions were found to be more effective for reducing the sheet resistance and enlarging the work function of graphene for effective charge separation and transport, and the efficiency was increased to 9.2% by a factor of 1.68 under AM 1.5 illumination.
Co-reporter:Pengzhan Sun, Miao Zhu, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu, and Hongwei Zhu
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 19) pp:9563
Publication Date(Web):September 9, 2013
DOI:10.1021/am403186r
Materials with low temperature coefficient of resistivity (TCR) are of great importance in some areas, for example, highly accurate electronic measurement instruments and microelectronic integrated circuits. In this work, we demonstrated the ultrathin graphene–graphene oxide (GO) hybrid films prepared by layer-by-layer assembly with very small TCR (30–100 °C) in the air. Electrical response of the hybrid films to temperature variation was investigated along with the progressive reduction of GO sheets. The mechanism of electrical response to temperature variation of the hybrid film was discussed, which revealed that the interaction between graphene and GO and the chemical doping effect were responsible for the tunable control of its electrical response to temperature variation. The unique properties of graphene–GO hybrid film made it a promising candidate in many areas, such as high-end film electronic device and sensor applications.Keywords: graphene; graphene oxide; hybrid; temperature coefficient of resistivity;
Co-reporter:Xiaoyang Hu, Yingjiu Zhang, Hiroki Ago, Huihua Zhou, Xiao Li, Lili Fan, Bin Cai, Xinjian Li, Minlin Zhong, Kunlin Wang, Dehai Wu, Hongwei Zhu
Carbon 2013 Volume 61() pp:299-304
Publication Date(Web):September 2013
DOI:10.1016/j.carbon.2013.05.008
Large-scale few-layer graphene (FLG) films were prepared by an industrial single-roller melt spinning technique based on molten alloy quenched carbon self-segregation using nickel and carbon as precursors. A formation mechanism of FLG based on rapid diffusion and non-equilibrium segregation of carbon is discussed. This ultra-fast thin film preparation technique can be extended and used to produce ultrathin sheets of two-dimensional materials other than graphene.
Co-reporter:Yachang Cao, Miao Zhu, Peixu Li, Rujing Zhang, Xinming Li, Qianming Gong, Kunling Wang, Minlin Zhong, Dehai Wu, Feng Lin and Hongwei Zhu
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 45) pp:19550-19556
Publication Date(Web):07 Oct 2013
DOI:10.1039/C3CP54017K
Modifying conventional materials with new recipes represents a straightforward yet efficient way to realize large-scale applications of new materials. Electrochemically reduced graphene oxide (ERGO) coated carbon fibres (CFs), prepared as fibre-like supercapacitor electrodes, exhibited excellent electrochemical energy storage performance. Upon addition of only a small amount (∼1 wt%) of ERGO, the hybrid fibres showed superior electrochemical capacitances (nearly three orders of magnitude enhanced) compared to pure CFs in both aqueous and gel electrolytes. Meanwhile, the energy density did not decrease notably as the power density increased. The superior capacitive performance could be attributed to the synergistic effect between wrinkled and porous ERGO sheets and highly conductive CFs. This fibre electrode material also offered advantages such as easy operation, mass production capability, mechanical flexibility and robustness, and could have an impact on a wide variety of potential applications in energy and electronic fields.
Co-reporter:Xinming Li, Tianshuo Zhao, Qiao Chen, Peixu Li, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu, Bingqing Wei and Hongwei Zhu
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 41) pp:17752-17757
Publication Date(Web):03 Sep 2013
DOI:10.1039/C3CP52908H
Flexible all-solid-state supercapacitors based on graphene fibers are demonstrated in this study. Surface-deposited oxide nanoparticles are used as pseudo-capacitor electrodes to achieve high capacitance. This supercapacitor electrode has an areal capacitance of 42 mF cm−2, which is comparable to the capacitance for fiber-based supercapacitors reported to date. During the bending and cycling of the fiber-based supercapacitor, the stability could be maintained without sacrificing the electrochemical performance, which provides a novel and simple way to develop flexible, lightweight and efficient graphene-based devices.
Co-reporter:Liancheng Wang, Yiyun Zhang, Xiao Li, Enqing Guo, Zhiqiang Liu, Xiaoyan Yi, Hongwei Zhu and Guohong Wang
RSC Advances 2013 vol. 3(Issue 10) pp:3359-3364
Publication Date(Web):04 Jan 2013
DOI:10.1039/C2RA22170E
Electrical characteristics of p-, n-GaN/graphene junctions before and after nitric acid doping have been investigated. Acid treatment can significantly improve the junction conductance in both cases, which is advantageous for the light emitting diode (LED) to reduce the operating voltage. GaN-based vertical LEDs incorporating graphene as transparent electrodes are further assembled and tested, showing significant improvement in forward electrical characteristics and light output power upon acid modification.
Co-reporter:Pengzhan Sun, Miao Zhu, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu, Zhiping Xu, and Hongwei Zhu
ACS Nano 2013 Volume 7(Issue 1) pp:428
Publication Date(Web):December 7, 2012
DOI:10.1021/nn304471w
The selective ion penetration and water purification properties of freestanding graphene oxide (GO) membranes are demonstrated. Sodium salts permeated through GO membranes quickly, whereas heavy-metal salts infiltrated much more slowly. Interestingly, copper salts were entirely blocked by GO membranes, and organic contaminants also did not infiltrate. The mechanism of the selective ion-penetration properties of the GO membranes is discussed. The nanocapillaries formed within the membranes were responsible for the permeation of metal ions, whereas the coordination between heavy-metal ions with the GO membranes restricted the passage of the ions. Finally, the penetration processes of hybrid aqueous solutions were investigated; the results revealed that sodium salts can be separated effectively from copper salts and organic contaminants. The presented results demonstrate the potential applications of GO in areas such as barrier separation and water purification.Keywords: graphene oxides; ion penetration; water treatment
Co-reporter:Jing Zhong, Zhenyu Yang, Rahul Mukherjee, Abhay Varghese Thomas, Ke Zhu, Pengzhan Sun, Jie Lian, Hongwei Zhu, Nikhil Koratkar
Nano Energy 2013 Volume 2(Issue 5) pp:1025-1030
Publication Date(Web):September 2013
DOI:10.1016/j.nanoen.2013.04.001
•Carbon nanotube sponges as conductive networks for pseudo-capacitors.•High porosity of nanotube sponge enables uniform polyaniline deposition.•No need for any conductive additives or mechanical binders.•Excellent areal capacitance coupled with high rate capability and cycle stability.We explored supercapacitor devices by utilizing 3-D highly porous (with average pore size of ∼80 nm) carbon nanotube sponges as a conductive substrate for polyaniline deposition. The porous structure of the sponge is beneficial for precursor penetration and uniform deposition of polyaniline on to the nanotubes. The self-supported, free-standing and flexible carbon nanotube polyaniline composite structure does not require any conductive additives or mechanical binders and delivers excellent areal capacitance (1.85–1.62 F/cm2 in the 4.9–49 mA/cm2 current density range) coupled with high rate capability and cycle stability.Scanning electron microscopy images of uncoated (left) and polyaniline coated carbon nanotube sponges (right). The high porosity of the nanotube sponge enables the uniform deposition of polyaniline even in a ∼1 mm thick electrode. The three-dimensional, porous, self-supported and flexible carbon nanotube sponge acts as a conductive network for the polyaniline pseudo-capacitor device eliminating the need for any conductive additives or mechanical binders. The resulting pseudo-capacitor offers an excellent areal capacitance coupled with high rate capability and cycle stability.
Co-reporter:Xiao Li;Lili Fan;Zhen Li;Kunlin Wang;Minlin Zhong;Jinquan Wei;Dehai Wu
Advanced Energy Materials 2012 Volume 2( Issue 4) pp:425-429
Publication Date(Web):
DOI:10.1002/aenm.201100671
Co-reporter:Yongyuan Zang, Dan Xie, Yu Chen, Xiao Wu, Tianling Ren, Jinquan Wei, Hongwei Zhu and David Plant
Nanoscale 2012 vol. 4(Issue 9) pp:2926-2930
Publication Date(Web):02 Mar 2012
DOI:10.1039/C2NR30084B
Electrical and thermal properties of a carbon nanotube (CNT)/multiferroic BiFeO3 (BFO)/Pt photovoltaic heterojunction are investigated for the first time. Enhanced photovoltaic properties (Jsc ≈ 2.1 μA cm−2 and Voc ≈ 0.47 V), as compared to the traditional polycrystalline BFO with indium tin oxide (ITO) as the top electrode, are observed due to the unique properties of CNT. An equivalent electrical and thermal model is constructed based on the energy band diagram of the CNT/BFO/Pt heterojunction for the first time and the carriers' transportation behavior is depicted theoretically. The influence of CdSe quantum dots (QDs) sensitization on the photovoltaic properties is presented, and a clear improvement of ∼4 fold in photocurrent density is observed.
Co-reporter:Yiyun Zhang, Xiao Li, Liancheng Wang, Xiaoyan Yi, Dehai Wu, Hongwei Zhu and Guohong Wang
Nanoscale 2012 vol. 4(Issue 19) pp:5852-5855
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2NR31986A
A NiOx buffer layer is introduced in GaN-based light-emitting diodes to form low resistance ohmic contacts between p-type GaN and graphene conductive electrodes, leading to improved performance with lower operating voltage and higher light output power.
Co-reporter:Guifeng Fan, Lili Fan, Zhen Li, Xi Bai, Stephen Mulligan, Yi Jia, Kunlin Wang, Jinquan Wei, Anyuan Cao, Dehai Wu, Bingqing Wei and Hongwei Zhu
Journal of Materials Chemistry A 2012 vol. 22(Issue 8) pp:3330-3334
Publication Date(Web):20 Jan 2012
DOI:10.1039/C2JM15938D
We study the gas flow assisted photovoltaic behaviour of the carbon/Si Schottky solar cells and reveal a hybrid effect with a flow-induced enhancement in cell efficiency. Gas flow sensing using the carbon/Si solar cells is proposed and tested.
Co-reporter:Pengzhan Sun, Renzhi Ma, Minoru Osada, Takayoshi Sasaki, Jinquan Wei, Kunlin Wang, Dehai Wu, Yao Cheng, Hongwei Zhu
Carbon 2012 Volume 50(Issue 12) pp:4518-4523
Publication Date(Web):October 2012
DOI:10.1016/j.carbon.2012.05.035
We report the fabrication of hybrid films of graphene and monolayer titania using a simple electrostatic self-assembly method. Ultraviolet (UV) responses of the hybrid films based on the graphene–titania structure were investigated. We observed that the resistance of the graphene–titania hybrid increased exponentially with UV irradiation time and decreased exponentially when UV was turned off. Time constants of the order of hundreds of seconds were identified and found to be sensitive to the gas environment of graphene. The UV response as well as the time constant is tunable by varying the number of titania layers. Our results confirmed that UV irradiation played a significant role in the resistance modulation of graphene as well as graphene–titania hybrid films.
Co-reporter:Pengzhan Sun, Miao Zhu, Renzhi Ma, Kunlin Wang, Jinquan Wei, Dehai Wu, Takayoshi Sasaki and Hongwei Zhu
RSC Advances 2012 vol. 2(Issue 29) pp:10829-10835
Publication Date(Web):03 Sep 2012
DOI:10.1039/C2RA21699J
Ultrathin hybrid films of graphene oxide (GO) and monolayer titania (TO) were assembled by layer-by-layer and drop-casting methods. The photo-induced wettability modulation of the hybrid films with different configurations was systematically studied. Due to the photocatalytic reduction of GO by TO, GO sheets in the hybrid films exhibited a tendency to undergo photo-induced conversion from hydrophilic to hydrophobic upon UV irradiation. On the contrary, TO nanosheets showed the reverse trend. Both surfaces of the hybrid film showed opposite yet tunable hydrophilicity under UV irradiation, demonstrating the potential for future application in liquid transport engineering.
Co-reporter:Lili Fan;Xueliu Fan;Jinquan Wei;Kunlin Wang;Dehai Wu
Chemical Vapor Deposition 2012 Volume 18( Issue 7-9) pp:185-190
Publication Date(Web):
DOI:10.1002/cvde.201206984
Abstract
The CVD of graphene on metal substrates serves as an ideal platform for studying the nucleation and growth of two-dimensional crystals. In this paper, the size distribution and shape transformation of graphene domains at early stages of CVD are investigated. The transformation of round-shaped graphene disks into hexagonal domains during atmospheric pressure (AP)CVD on copper substrates is identified. The critical transformation size from graphene disks to hexagonal domains is ∼0.8 µm2 according to the size distribution statistics.
Co-reporter:Lili Fan, Zhen Li, Xiao Li, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu and Hongwei Zhu
Nanoscale 2011 vol. 3(Issue 12) pp:4946-4950
Publication Date(Web):04 Nov 2011
DOI:10.1039/C1NR11480H
Graphene domains in different shapes have been grown on copper substrates viaatmospheric pressure chemical vapour deposition by controlling the growth process parameters. Under stabilized conditions, graphene domains tend to be six-fold symmetric hexagons under low flow rate methane with some domains in an irregular hexagonal shape. After further varying the growth duration, methane flow rate, and temperature, graphene domains have developed shapes from hexagon to shovel and dendrite. Two connecting modes, through overlap and merging of adjacent graphene domains, are proposed.
Co-reporter:Zhen Li, Peng Zhang, Kunlin Wang, Zhiping Xu, Jinquan Wei, Lili Fan, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2011 vol. 21(Issue 35) pp:13241-13246
Publication Date(Web):01 Aug 2011
DOI:10.1039/C1JM11695A
We report an in situ synthesis of graphene–metal hybrids using graphene as the buffer layer by a substrate-induced galvanic reaction. Ag nanoplates are obtained with the template effect of graphene, and their morphologies are tailored by light mediation. Our result suggests that defect sites or open edges of graphene favor binding with Ag atoms. The graphene–Ag hybrids have been used as Raman enhanced substrates for dye detection. The facile method for synthesis of graphene–metal hybrids opens up opportunities for the future development of optical, electronic and catalytic materials based on graphene and metals.
Co-reporter:Guifeng Fan, Hongwei Zhu, Kunlin Wang, Jinquan Wei, Xinming Li, Qinke Shu, Ning Guo, and Dehai Wu
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 3) pp:721
Publication Date(Web):February 16, 2011
DOI:10.1021/am1010354
Schottky junction solar cells are assembled by directly coating graphene films on n-type silicon nanowire (SiNW) arrays. The graphene/SiNW junction shows enhanced light trapping and faster carrier transport compared to the graphene/planar Si structure. With chemical doping, the SiNW-based solar cells showed energy conversion efficiencies of up to 2.86% at AM1.5 condition, opening a possibility of using graphene/semiconductor nanostructures in photovoltaic application.Keywords: graphene; Schottky junctions; silicon nanowires; solar cells
Co-reporter:Zhen Li, Hongwei Zhu, Dan Xie, Kunlin Wang, Anyuan Cao, Jinquan Wei, Xiao Li, Lili Fan and Dehai Wu
Chemical Communications 2011 vol. 47(Issue 12) pp:3520-3522
Publication Date(Web):10 Feb 2011
DOI:10.1039/C0CC05139J
We report a fast (in 10–40 s) flame synthesis of high quality few-layered graphene/graphite films, offering the advantages of simplicity, high efficiency, energy saving, low cost and the ability to extend to continuous and mass production of graphene.
Co-reporter:Zhen Li, Hongwei Zhu, Kunlin Wang, Jinquan Wei, Xuchun Gui, Xiao Li, Chunyan Li, Lili Fan, Pengzhan Sun, Dehai Wu
Carbon 2011 Volume 49(Issue 1) pp:237-241
Publication Date(Web):January 2011
DOI:10.1016/j.carbon.2010.09.009
Large area (the order of centimeters), flexible thin films of amorphous carbon were prepared on copper foils by an ethanol flame synthesis method. The carbon films exhibit high transmittance in the visible and near infrared range (up to 90% at 550 nm). Schottky diodes formed by combining the carbon films with n-type silicon wafers show high on/off ratio (up to 150) photocurrents at air-mass 1.5 and illumination intensity of 100 mW/cm2.Graphical abstract■■■Research highlights► Large area (the order of centimeters), flexible thin films of amorphous carbon were prepared on copper foils by an ethanol flame synthesis method. The carbon films exhibit high transmittance in the visible and near infrared range (up to 90% at 550 nm).
Co-reporter:Xuchun Gui, Hongbian Li, Kunlin Wang, Jinquan Wei, Yi Jia, Zhen Li, Lili Fan, Anyuan Cao, Hongwei Zhu, Dehai Wu
Acta Materialia 2011 Volume 59(Issue 12) pp:4798-4804
Publication Date(Web):July 2011
DOI:10.1016/j.actamat.2011.04.022
Abstract
The recyclability of carbon nanotube (CNT) sponges in terms of oil absorption was studied. The sorption capacities of these sponges are greater than 100 g g–1 for many organics and oils with viscosities of 3–200 cP, and they maintain sorption capacities of 20–40 g g–1 after 10 cycles of absorption. About 98% of absorbed oil can be recovered by squeezing or converted to heat by directly burning the oil within the sponges. The sorption process has been described by a second-order kinetic model. The results demonstrate that CNT sponges are promising oil sorbents with good recyclability.
Co-reporter:Xinming Li, Tianshuo Zhao, Kunlin Wang, Ying Yang, Jinquan Wei, Feiyu Kang, Dehai Wu, and Hongwei Zhu
Langmuir 2011 Volume 27(Issue 19) pp:12164-12171
Publication Date(Web):August 29, 2011
DOI:10.1021/la202380g
Integration of graphene into macroscopic architectures represents the first step toward creating a new class of graphene-based nanodevices. We report a novel yet simple approach to fabricate graphene fibers, a porous and monolithic macrostructure, from chemical vapor deposition grown graphene films. Graphene is first self-assembled from a 2D film to a 1D fiberlike structure in an organic solvent (e.g., ethanol, acetone) and then dried to give the porous and crumpled structure. The method developed here is scalable and controllable, delivering tunable morphology and pore structure by controlling the evaporation of solvents with suitable surface tension. The fibers are 20–50 μm thick, with a typical electrical conductivity of ∼1000 S/m. The cyclic voltammetric studies show typical capacitive behavior for the porous graphene fibers with good rate stability and capacitance values ranging from 0.6 to 1.4 mF/cm2. Decorated with only 1–3 wt % MnO2, the graphene/MnO2 composites exhibit remarkable enhancement of combined performance both with respect to discharge capacitance (up to 12.4 mF/cm2) and cycling stability. This special structure could facilitate chemical doping and electrochemical energy storage and find applications in catalyst supports, sensors, supercapacitors, Li ion batteries, etc.
Co-reporter:Xuchun Gui, Hongbian Li, Luhui Zhang, Yi Jia, Li Liu, Zhen Li, Jinquan Wei, Kunlin Wang, Hongwei Zhu, Zikang Tang, Dehai Wu, and Anyuan Cao
ACS Nano 2011 Volume 5(Issue 6) pp:4276
Publication Date(Web):May 19, 2011
DOI:10.1021/nn201002d
Fabrication of high-performance nanocomposites requires that the nanoscale fillers be dispersed uniformly and form a continuous network throughout the matrix. Direct infiltration of porous CNT sponges consisting of a three-dimensional nanotube scaffold may provide a possible solution to this challenge. Here, we fabricated CNT sponge nanocomposites by directly infiltrating epoxy fluid into the CNT framework while maintaining the original network structure and CNT contact, with simultaneous improvement in mechanical and electrical properties. The resulting composites have an isotropic structure with electrical resistivities of 10 to 30 Ω·cm along arbitrary directions, much higher than traditional composites by mixing random CNTs with epoxy matrix. We observed reversible resistance change in the sponge composites under compression at modest strains, which can be explained by tunneling conduction model, suggesting potential applications in electromechanical sensors.Keywords: carbon nanotubes; electromechanical device; isotropic property; nanocomposites; sponges
Co-reporter:Luhui Zhang;Lili Fan;Zhen Li;Enzheng Shi;Xinming Li;Hongbian Li
Nano Research 2011 Volume 4( Issue 9) pp:891-900
Publication Date(Web):2011 September
DOI:10.1007/s12274-011-0145-6
Co-reporter:Xinming Li;Kunlin Wang;Anyuan Cao;Jinquan Wei;Chunyan Li;Yi Jia;Zhen Li;Xiao Li;Dehai Wu
Advanced Materials 2010 Volume 22( Issue 25) pp:2743-2748
Publication Date(Web):
DOI:10.1002/adma.200904383
Co-reporter:Qinke Shu, Jinquan Wei, Kunlin Wang, Shuang Song, Ning Guo, Yi Jia, Zhen Li, Ying Xu, Anyuan Cao, Hongwei Zhu and Dehai Wu
Chemical Communications 2010 vol. 46(Issue 30) pp:5533-5535
Publication Date(Web):24 Jun 2010
DOI:10.1039/C0CC00512F
Hybrid photoelectrochemistry and heterojunction solar cells made from carbon nanotubes and silicon nanowires show high energy conversion efficiencies of up to 6%.
Co-reporter:Xiao Li, Chunyan Li, Hongwei Zhu, Kunlin Wang, Jinquan Wei, Xinming Li, Eryang Xu, Zhen Li, Shu Luo, Yu Lei and Dehai Wu
Chemical Communications 2010 vol. 46(Issue 20) pp:3502-3504
Publication Date(Web):07 Apr 2010
DOI:10.1039/C002092C
A new form of hybrid carbon-based thin film was prepared via a pyridine chemical vapour deposition method. The as-obtained films consist of agglomerated flowerlike graphene nanowhiskers embedded in a uniform matrix of amorphous carbon. Schottky solar cells made from the hybrid films and n-type silicon show conversion efficiencies of ∼1% under AM 1.5 illumination.
Co-reporter:Eryang Xu, Jinquan Wei, Kunlin Wang, Zhen Li, Xuchun Gui, Yi Jia, Hongwei Zhu, Dehai Wu
Carbon 2010 Volume 48(Issue 11) pp:3097-3102
Publication Date(Web):September 2010
DOI:10.1016/j.carbon.2010.04.046
Carbon nanotube (CNT) arrays doped with nitrogen were synthesized using chemical vapor deposition by pyrolysis of xylene/pyridine and ferrocene with a modified precursor feeding technique. The system produced a gradient of nitrogen concentration that modified the CNTs from a hollow cylinder to a bamboo-shaped structure which contains a series of compartments whose lengths are gradually reduced as the nitrogen concentration increases.
Co-reporter:Xuchun Gui, Jinquan Wei, Kunlin Wang, Eryang Xu, Ruitao Lv, Dan Zhu, Zhigang Guo, Feiyu Kang, Yanqiu Zhu, Dejie Li, Hongwei Zhu, Dehai Wu
Materials Research Bulletin 2010 45(5) pp: 568-571
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.01.015
Co-reporter:Yi Jia, Peixu Li, Jinquan Wei, Anyuan Cao, Kunlin Wang, Chunlei Li, Daming Zhuang, Hongwei Zhu, Dehai Wu
Materials Research Bulletin 2010 45(10) pp: 1401-1405
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.06.045
Co-reporter:Wentian Gu, Wei Zhang, Xinming Li, Hongwei Zhu, Jinquan Wei, Zhen Li, Qinke Shu, Chen Wang, Kunlin Wang, Wanci Shen, Feiyu Kang and Dehai Wu
Journal of Materials Chemistry A 2009 vol. 19(Issue 21) pp:3367-3369
Publication Date(Web):30 Apr 2009
DOI:10.1039/B904093P
High quality graphene sheets have been prepared by a facile liquid phase exfoliation of worm-like graphite (WEG). This approach combining with the advances in large scale industry manufacturing of WEG could potentially lead to the development of new and more effective graphene products.
Co-reporter:Chunyan Li, Hongwei Zhu, Kazutomo Suenaga, Jinquan Wei, Kunlin Wang, Dehai Wu
Materials Letters 2009 Volume 63(Issue 15) pp:1366-1369
Publication Date(Web):15 June 2009
DOI:10.1016/j.matlet.2009.03.025
Two different growth modes of carbon nanotubes (CNTs) are identified in ethylene chemical vapour deposition (CVD) using SiO2 as support. With a series of electron microscopy observations, we have found that small-diameter nanotubes favor a root-growth mechanism on nanoporous SiO2 support, while nanotubes with larger diameters prefer a tip-growth. The dependence of growth mode on tube diameter is explained in terms of the porosity of the support and the size distribution of the catalyst. Our results provide clues to control growth of CNTs and obtain well-organized nanotube structures.
Co-reporter:Xiao Li, Chunyan Li, Xinming Li, Hongwei Zhu, Jinquan Wei, Kunlin Wang, Dehai Wu
Chemical Physics Letters 2009 Volume 481(4–6) pp:224-228
Publication Date(Web):28 October 2009
DOI:10.1016/j.cplett.2009.09.097
Abstract
Pure carbon bulk junctions are fabricated based on carbon nanotube (CNT) macrostructures and their electrical transport characteristics are investigated. The planar 1D/2D strand-on-film (SOF) junctions show interesting force- and light-controlled transport behaviors. Considering the excellent chemical stability and good mechanical properties (strength, hardness and elasticity) of CNTs, the SOF junctions could find practical and wide applications in electromechanical and optoelectronic devices.
Co-reporter:Hongwei Zhu, Jinquan Wei, Kunlin Wang, Dehai Wu
Solar Energy Materials and Solar Cells 2009 93(9) pp: 1461-1470
Publication Date(Web):
DOI:10.1016/j.solmat.2009.04.006
Co-reporter:Hongwei Zhu, Charan Masarapu, Jinquan Wei, Kunlin Wang, Dehai Wu, Bingqing Wei
Physica E: Low-dimensional Systems and Nanostructures 2009 Volume 41(Issue 7) pp:1277-1280
Publication Date(Web):June 2009
DOI:10.1016/j.physe.2009.02.010
Temperature dependence of the field-emission characteristics is investigated for the purified single-walled carbon nanotube (SWNT) thin films. The turn-on field and work function decrease with increasing temperature. It is considered that an increase of the carrier concentration with increasing temperature leads to a reduction in the tunnel barrier width, resulting in an enhancement of the emission current.
Co-reporter:Hongwei Zhu ; ; Kazutomo Suenaga ; ; Jinquan Wei ; ; Kunlin Wang ; ;Dehai Wu ;
The Journal of Physical Chemistry C 2008 Volume 112(Issue 30) pp:11098-11101
Publication Date(Web):July 4, 2008
DOI:10.1021/jp804385a
Atomic configurations of individual single-walled and double-walled carbon nanotubes have been obtained by high-resolution transmission electron microscopy with atomic sensitivity. A structural reconstruction is carried out by Fourier-filtered analysis of Moiré patterns, and it is now possible to acquire the carbon honeycomb lattice images through all of the periphery of individual nanotubes. This visualization technique provides supplementary access in nanoscale characterizations by combining with scanning tunneling microscopy.
Co-reporter:Guoke Zhao, Xinming Li, Meirong Huang, Zhen Zhen, Yujia Zhong, Qiao Chen, Xuanliang Zhao, Yijia He, Ruirui Hu, Tingting Yang, Rujing Zhang, Changli Li, Jing Kong, Jian-Bin Xu, Rodney S. Ruoff and Hongwei Zhu
Chemical Society Reviews 2017 - vol. 46(Issue 15) pp:NaN4449-4449
Publication Date(Web):2017/07/05
DOI:10.1039/C7CS00256D
Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major “graphene-on-surface” structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.
Co-reporter:Xiao Li, Li Zhang, Meirong Huang, Shuying Wang, Xinming Li and Hongwei Zhu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 38) pp:NaN14795-14795
Publication Date(Web):2016/08/31
DOI:10.1039/C6TA07009D
The development of efficient and low-cost solar-driven overall water splitting systems for sustainable hydrogen generation is still a challenge. Herein, cobalt and nickel (Co and Ni) selenide nanowalls have been prepared on a conductive graphene coated Ni mesh substrate and used as electrocatalysts for hydrogen generation and oxygen evolution. The bifunctional CoSe nanowalls showed a high electrochemically active surface area, which manifested a low onset potential and high structural stability for overall water splitting. It afforded a 10 mA cm−2 current density at −78 mV vs. RHE for the hydrogen evolution reaction and 150 mA cm−2 at 1.74 V vs. RHE for the oxygen evolution reaction. No significant degradation was observed after a 24 h chronoamperometric test. A solar water electrolysis system was constructed by connecting the CoSe (+) and CoSe (−) pair with a photovoltaic cell in tandem, which showed a highest solar-to-hydrogen conversion efficiency of 6.65%. Its superior performance over industrial water electrolyzers provided a new possibility towards clean energy storage and utilization.
Co-reporter:Pengzhan Sun, Renzhi Ma, Hui Deng, Zhigong Song, Zhen Zhen, Kunlin Wang, Takayoshi Sasaki, Zhiping Xu and Hongwei Zhu
Chemical Science (2010-Present) 2016 - vol. 7(Issue 12) pp:NaN6994-6994
Publication Date(Web):2016/07/20
DOI:10.1039/C6SC02865A
Although graphene oxide lamellar membranes (GOLMs) are effective in blocking large organic molecules and nanoparticles for nanofiltration and ultrafiltration, water desalination with GOLM is challenging, with seriously controversial results. Here, a combined experimental and molecular dynamics simulation study shows that intrinsic high water/ion selectivity of GOLM was achieved in concentration gradient-driven diffusion, showing great promise in water desalination. However, in pressure-driven filtration the salt rejection was poor. This study unveils a long-overlooked reason behind the controversy in water desalination with GOLM and further provides a fundamental understanding on the in-depth mechanism concerning the strong correlation of water/ion selectivity with the applied pressure and GO nanochannel length. Our calculations and experiments show that the applied pressure weakened the water–ion interactions in GO nanochannels and reduced their permeation selectivity, while the length of nanochannels dominated the mass transport processes and the ion selectivity. The new insights presented here may open up new opportunities for the optimization of GOLMs in this challenging area.
Co-reporter:Xiao Li, Chunyan Li, Hongwei Zhu, Kunlin Wang, Jinquan Wei, Xinming Li, Eryang Xu, Zhen Li, Shu Luo, Yu Lei and Dehai Wu
Chemical Communications 2010 - vol. 46(Issue 20) pp:NaN3504-3504
Publication Date(Web):2010/04/07
DOI:10.1039/C002092C
A new form of hybrid carbon-based thin film was prepared via a pyridine chemical vapour deposition method. The as-obtained films consist of agglomerated flowerlike graphene nanowhiskers embedded in a uniform matrix of amorphous carbon. Schottky solar cells made from the hybrid films and n-type silicon show conversion efficiencies of ∼1% under AM 1.5 illumination.
Co-reporter:Pengzhan Sun, Kunlin Wang, Jinquan Wei, Minlin Zhong, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 21) pp:NaN7737-7737
Publication Date(Web):2014/03/31
DOI:10.1039/C4TA00668B
The efficient recovery of acids from iron-based electrolytes using graphene oxide (GO) membranes was demonstrated for the first time. The results revealed that the amount of H+ permeating the GO membranes and reaching drains was two orders of magnitude larger than that of Fe3+. Notably, when the FeCl3 source concentration was reduced to certain extent, Fe3+ could be completely blocked by GO membranes. The mechanism for the effective separation of H+ from Fe3+ was studied, suggesting that the molecular sieving effect of GO nanocapillaries and the coordination between Fe3+ and GO were responsible for the effective blockage of Fe3+ while the rapid propagation of H+ through hydrogen-bonding networks along water layers within the interlayer spacing was responsible for the fast migration of H+. These properties made GO membranes promising cation-exchange membranes for applications of wastewater reuse and membrane separation.
Co-reporter:Lili Fan, Kunlin Wang, Jinquan Wei, Minlin Zhong, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 32) pp:NaN13128-13128
Publication Date(Web):2014/06/13
DOI:10.1039/C4TA01975J
Nanoparticles are ubiquitously existent on the surface of graphene films prepared by chemical vapour deposition. However, studies that thoroughly explore this phenomenon are still fairly limited. In this work, we have demonstrated that the location of nanoparticles should be a straightforward reflection of the nucleation sites of graphene growth. In addition, the deposition of nanoparticles is consistent with the distribution of multilayer graphene. We have found that nanoparticles are not nucleation seeds as proposed by other groups; instead, they are sediment-like materials similar to the graphene films prepared on copper substrates.
Co-reporter:Zhen Li, Peng Zhang, Kunlin Wang, Zhiping Xu, Jinquan Wei, Lili Fan, Dehai Wu and Hongwei Zhu
Journal of Materials Chemistry A 2011 - vol. 21(Issue 35) pp:NaN13246-13246
Publication Date(Web):2011/08/01
DOI:10.1039/C1JM11695A
We report an in situ synthesis of graphene–metal hybrids using graphene as the buffer layer by a substrate-induced galvanic reaction. Ag nanoplates are obtained with the template effect of graphene, and their morphologies are tailored by light mediation. Our result suggests that defect sites or open edges of graphene favor binding with Ag atoms. The graphene–Ag hybrids have been used as Raman enhanced substrates for dye detection. The facile method for synthesis of graphene–metal hybrids opens up opportunities for the future development of optical, electronic and catalytic materials based on graphene and metals.
Co-reporter:Wentian Gu, Wei Zhang, Xinming Li, Hongwei Zhu, Jinquan Wei, Zhen Li, Qinke Shu, Chen Wang, Kunlin Wang, Wanci Shen, Feiyu Kang and Dehai Wu
Journal of Materials Chemistry A 2009 - vol. 19(Issue 21) pp:NaN3369-3369
Publication Date(Web):2009/04/30
DOI:10.1039/B904093P
High quality graphene sheets have been prepared by a facile liquid phase exfoliation of worm-like graphite (WEG). This approach combining with the advances in large scale industry manufacturing of WEG could potentially lead to the development of new and more effective graphene products.
Co-reporter:Yachang Cao, Miao Zhu, Peixu Li, Rujing Zhang, Xinming Li, Qianming Gong, Kunling Wang, Minlin Zhong, Dehai Wu, Feng Lin and Hongwei Zhu
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 45) pp:NaN19556-19556
Publication Date(Web):2013/10/07
DOI:10.1039/C3CP54017K
Modifying conventional materials with new recipes represents a straightforward yet efficient way to realize large-scale applications of new materials. Electrochemically reduced graphene oxide (ERGO) coated carbon fibres (CFs), prepared as fibre-like supercapacitor electrodes, exhibited excellent electrochemical energy storage performance. Upon addition of only a small amount (∼1 wt%) of ERGO, the hybrid fibres showed superior electrochemical capacitances (nearly three orders of magnitude enhanced) compared to pure CFs in both aqueous and gel electrolytes. Meanwhile, the energy density did not decrease notably as the power density increased. The superior capacitive performance could be attributed to the synergistic effect between wrinkled and porous ERGO sheets and highly conductive CFs. This fibre electrode material also offered advantages such as easy operation, mass production capability, mechanical flexibility and robustness, and could have an impact on a wide variety of potential applications in energy and electronic fields.
Co-reporter:Xinming Li, Tianshuo Zhao, Qiao Chen, Peixu Li, Kunlin Wang, Minlin Zhong, Jinquan Wei, Dehai Wu, Bingqing Wei and Hongwei Zhu
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 41) pp:NaN17757-17757
Publication Date(Web):2013/09/03
DOI:10.1039/C3CP52908H
Flexible all-solid-state supercapacitors based on graphene fibers are demonstrated in this study. Surface-deposited oxide nanoparticles are used as pseudo-capacitor electrodes to achieve high capacitance. This supercapacitor electrode has an areal capacitance of 42 mF cm−2, which is comparable to the capacitance for fiber-based supercapacitors reported to date. During the bending and cycling of the fiber-based supercapacitor, the stability could be maintained without sacrificing the electrochemical performance, which provides a novel and simple way to develop flexible, lightweight and efficient graphene-based devices.
Co-reporter:Ning Wei, Cheng Chang, Hongwei Zhu and Zhiping Xu
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 22) pp:
Publication Date(Web):
DOI:10.1039/C3CP55063J
Co-reporter:Guifeng Fan, Lili Fan, Zhen Li, Xi Bai, Stephen Mulligan, Yi Jia, Kunlin Wang, Jinquan Wei, Anyuan Cao, Dehai Wu, Bingqing Wei and Hongwei Zhu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 8) pp:NaN3334-3334
Publication Date(Web):2012/01/20
DOI:10.1039/C2JM15938D
We study the gas flow assisted photovoltaic behaviour of the carbon/Si Schottky solar cells and reveal a hybrid effect with a flow-induced enhancement in cell efficiency. Gas flow sensing using the carbon/Si solar cells is proposed and tested.
Co-reporter:Miao Zhu, Li Zhang, Xinming Li, Yijia He, Xiao Li, Fengmei Guo, Xiaobei Zang, Kunlin Wang, Dan Xie, Xuanhua Li, Bingqing Wei and Hongwei Zhu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 15) pp:NaN8138-8138
Publication Date(Web):2015/03/11
DOI:10.1039/C5TA00702J
Graphene/Si has been proved to form a quality Schottky junction with high photoelectric conversion efficiency at AM 1.5. However, for the ultraviolet portion of the incident light, the photoelectric performance will degrade significantly due to severe absorption and recombination at the front surface. Herein, to realize enhanced ultraviolet detection with a graphene/Si diode, TiO2 nanoparticles (NPs, 3–5 nm) are synthesized and spin-coated on the graphene surface to improve the photoresponse in the ultraviolet region. According to our results, the conversion efficiency of the graphene/Si diode at 420 nm and 350 nm increases by 72.7% and 100% respectively with TiO2 coating. Then C−2–V measurements of both TiO2 and graphene/Si diode are performed to analyze the electronic band structure of the TiO2/graphene/Si system, based on which we finally present the enhancement mechanism of photodetection using TiO2 NPs.
Co-reporter:Qinke Shu, Jinquan Wei, Kunlin Wang, Shuang Song, Ning Guo, Yi Jia, Zhen Li, Ying Xu, Anyuan Cao, Hongwei Zhu and Dehai Wu
Chemical Communications 2010 - vol. 46(Issue 30) pp:NaN5535-5535
Publication Date(Web):2010/06/24
DOI:10.1039/C0CC00512F
Hybrid photoelectrochemistry and heterojunction solar cells made from carbon nanotubes and silicon nanowires show high energy conversion efficiencies of up to 6%.
Co-reporter:Zhen Li, Hongwei Zhu, Dan Xie, Kunlin Wang, Anyuan Cao, Jinquan Wei, Xiao Li, Lili Fan and Dehai Wu
Chemical Communications 2011 - vol. 47(Issue 12) pp:NaN3522-3522
Publication Date(Web):2011/02/10
DOI:10.1039/C0CC05139J
We report a fast (in 10–40 s) flame synthesis of high quality few-layered graphene/graphite films, offering the advantages of simplicity, high efficiency, energy saving, low cost and the ability to extend to continuous and mass production of graphene.
Co-reporter:Pengzhan Sun, He Liu, Kunlin Wang, Minlin Zhong, Dehai Wu and Hongwei Zhu
Chemical Communications 2015 - vol. 51(Issue 15) pp:NaN3254-3254
Publication Date(Web):2015/01/15
DOI:10.1039/C4CC10103K
Based on isotope labelling, we found that liquid water can afford an ultrafast permeation through graphene-based nanochannels with a diffusion coefficient 4–5 orders of magnitude greater than in the bulk case. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is slightly faster than water, indicating that the ions are mainly transported by water flows and the delicate interactions between ions and nanocapillary walls also take effect in the accelerated ion transportation.
