Co-reporter:Pei-Wen Chen, Kui Li, Yu-Xiang Yu, Wei-De Zhang
Applied Surface Science 2017 Volume 392() pp:608-615
Publication Date(Web):15 January 2017
DOI:10.1016/j.apsusc.2016.09.086
Highlights
- •
Cobalt-doped g-C3N4 photocatalysts were prepared.
- •
High and stable visible light photocatalytic activity for H2 evolution.
- •
Efficient separation and transfer of photo-induced electron-hole pairs.
Co-reporter:Feng-Yun Su
Chemistry – An Asian Journal 2017 Volume 12(Issue 5) pp:515-523
Publication Date(Web):2017/03/02
DOI:10.1002/asia.201601518
AbstractCarbonyl-grafted g-C3N4 porous nanosheets (COCNPNS) were fabricated by means of a two-step thermal process using melamine and oxalic acid as starting reagents. The combination of melamine with oxalic acid to form a melamine–oxalic acid supramolecule as a precursor is key to synthesizing carbonyl-grafted g-C3N4. The bulk carbonyl-grafted g-C3N4 (COCN) was further thermally etched onto porous nanosheets by O2 under air. In such a process, the carbonyl groups were partly removed and the obtained sample showed remarkably enhanced visible-light harvesting and promoted the separation and transfer of photogenerated electrons and holes. With its unique porous structure and enhanced light-harvesting capability, under visible-light illumination (λ>420 nm) the prepared COCNPNS exhibited a superior photocatalytic hydrogen evolution rate of 83.6 μmol h−1, which is 26 times that of the p-CN obtained directly from thermal polycondensation of melamine.
Co-reporter:Yong-Hao Xiao, Wei-De Zhang
Electrochimica Acta 2017 Volume 252(Volume 252) pp:
Publication Date(Web):20 October 2017
DOI:10.1016/j.electacta.2017.09.011
•MoS2 QDs-modified WO3 nanoplatelet arrays photoanode was successfully fabricated.•Modification of MoS2 QDs on WO3 significantly enhanced the PEC activity.•Photogenerated electrons and holes are efficiently separated.•The absorption light region was broadened and more active sites were provided.Facing the issues for ineffective visible light utilization, insufficient separation of photogenerated electron-hole pairs of WO3 photoanode, herein, ultrasmall MoS2 quantum dots (QDs) are exploited as surface sensitizers to boost the photoelectrochemical (PEC) properties of MoS2/WO3. The MoS2/WO3 photoanode is prepared by decorating 2D WO3 nanoplatelet arrays with ultra-small MoS2 QDs via a facile and effective assembly method. The interspersing of MoS2 QDs, not only broadens the photoabsorption region, but also provides more active sites for the surface reactions and enhances charge separation of the photogenerated electron-hole pairs, leading to a 2.13-fold enhancement in photocurrent density at 1.0 V vs. Ag/AgCl (1.23 V vs. RHE). MoS2/WO3 photoanodes hold potentialities for the straightforward building of molecular level devices for PEC production.MoS2 quantum dots-modified WO3 nanoplate arrays with high and stable photoelectrochemical activity under visible light were successfully prepared via a facile and effective assembly process. The modification of MoS2 QDs promotes the photoelectrochemical performance of WO3 toward water splitting.Download high-res image (186KB)Download full-size image
Co-reporter:Yong-Hao Xiao;Cheng-Qun Xu
Journal of Solid State Electrochemistry 2017 Volume 21( Issue 11) pp:3355-3364
Publication Date(Web):07 July 2017
DOI:10.1007/s10008-017-3680-6
A two-step hydrothermal process for preparing Ni-doped WO3 nanoplate arrays (NPAs) is developed, and the obtained samples were used as a photoanode to produce a highly active and stable electrocatalyst for photoelectrochemical (PEC) water splitting under visible light. The NPAs are formed as a single-phase solid solution with high purity. X-ray photoelectron spectroscopy measurement verifies the binding energy of W element is negatively shifted due to the substitution of W6+ by Ni2+ in the monoclinic lattice and thereby the formation of Ni-O-W bonds. Notably, the two-step 3 at% Ni-doped WO3 NPAs exhibits the highest PEC performance, compared with pure and one-step Ni-doped WO3 NPAs. At 1.0 V (vs Ag/AgCl), the current density of two-step 3 at% Ni-doped WO3 is 0.80 mA/cm2, which is about 1.74- and 2.35-fold of that of WO3 (0.46 mA/cm2) and one-step 3 at% Ni-doped WO3 (0.34 mA/cm2), respectively. The PEC performance of WO3 NPAs can be modified by Ni doping in a two-step hydrothermal process; both the changes of band gap and electrochemically active surface area (ECSA) are playing important roles on improving the activity of the WO3 NPAs photoanode.
Co-reporter:Ying Liu, Feng-Yun Su, Yu-Xiang Yu, Wei-De Zhang
International Journal of Hydrogen Energy 2016 Volume 41(Issue 18) pp:7270-7279
Publication Date(Web):18 May 2016
DOI:10.1016/j.ijhydene.2016.03.113
•Vertically aligned Ti-Fe2O3 nanosheets were grown on FTO by hydrothermal synthesis.•The Ti-Fe2O3 nanosheets were modified by nano g-C3N4.•g-C3N4/Ti-Fe2O3 heterojunction was constructed.•The photocurrent of the g-C3N4/Ti-Fe2O3 is 50 times as that of the Ti-Fe2O3.•Effectively separation of photogenerated electron–hole pairs.Considering the synergy effect between g-C3N4 and Ti-Fe2O3, the novel g-C3N4/Ti-Fe2O3 heterojuncted hybrids are constructed. g-C3N4 nanoparticles are prepared from bulk g-C3N4 via corrosion by strong acid and alkali, respectively, and then deposited onto Ti-Fe2O3 nanosheets. The physical and optical properties of the g-C3N4 modified Ti-Fe2O3 are characterized and the effect of g-C3N4 on the photoelectrochemical performance is studied. The photoelectrochemical activity of the Ti-Fe2O3 nanosheets is significantly enhanced upon the incorporation of g-C3N4 nanoparticles under visible light irradiation. The improved photoelectrochemical performance is ascribed to the synergy effect at the interface of the g-C3N4 and Ti-Fe2O3, including favorable contact, matched energy band levels of the two semiconductors and enhanced charge separation. Possible mechanism is proposed for the high photoelectrochemical activity of g-C3N4/Ti-Fe2O3 to guide the design of photoelectrodes.Nano g-C3N4 modified Ti-Fe2O3 nanosheet arrays with high and stable photoelectrochemical activity under visible light were successfully constructed. The heterostructured photoanode, g-C3N4 modified Ti-Fe2O3 nanosheet shows high photoelectrocatalytic activity toward water splitting.
Co-reporter:Xin Xie, Kui Li and Wei-De Zhang
RSC Advances 2016 vol. 6(Issue 78) pp:74234-74240
Publication Date(Web):28 Jul 2016
DOI:10.1039/C6RA11978F
Hematite (α-Fe2O3), with a relatively narrow bandgap (2.0–2.2 eV), is well-suited for potential application as a photoanode in photoelectrochemical (PEC) cells. Unfortunately, it suffers from severe bulk carrier recombination and low conductivity. This study provides a way to overcome these shortages by constructing a novel electrode system comprised of vertically aligned Ti-doped hematite nanosheet arrays decorated with cadmium sulfide nanoparticles (Ti-Fe2O3/CdS). Ti doping improves the conductivity of hematite and simultaneously extends the spectral responsive range. The incorporation of CdS nanoparticles further facilitates the charge separation and transfer process. Subsequently, the fabricated Ti-Fe2O3/CdS electrode achieves 6-fold enhancement of photocurrent density with respect to pristine Fe2O3 and excellent operation stability. Meanwhile, an obvious negative shift of photocurrent onset potential by 500 mV is observed.
Co-reporter:Ming Xu
European Journal of Inorganic Chemistry 2016 Volume 2016( Issue 6) pp:826-831
Publication Date(Web):
DOI:10.1002/ejic.201501260
Abstract
Bi2MoO6 microspheres were modified by loading AgI nanoparticles on their surfaces by a facile deposition/precipitation approach. The as-prepared AgI/Bi2MoO6 heterostructured photocatalysts exhibit much higher photocatalytic activities for the degradation of rhodamine B (RhB) and bisphenol A (BPA) than P25, AgI, Bi2MoO6, and a mechanical mixture of AgI and Bi2MoO6. The composite with 20 wt.-% AgI shows the highest degradation efficiency. The enhanced photocatalytic properties of the AgI/Bi2MoO6 heterostructures are attributed to their larger surface areas, extended absorption in the visible-light range, and efficient separation of photoinduced carriers at the interfaces of the AgI and Bi2MoO6 nanocrystals. The AgI/Bi2MoO6 photocatalyst is stable during the catalytic reaction and can be used repeatedly. Moreover, O2·– and h+ were verified as the main active species in the decomposition of organic pollutants. A possible photocatalytic mechanism is also proposed.
Co-reporter:Kui Li;Xin Xie ;Dr. Wei-De Zhang
ChemCatChem 2016 Volume 8( Issue 12) pp:2128-2135
Publication Date(Web):
DOI:10.1002/cctc.201600272
Abstract
A facile strategy to synthesize porous graphitic carbon nitride with stacking nanotubes by thermal condensation of melamine–ammonium oxalate stacking sheets is reported. The photocatalytic generation rate of hydrogen over the porous graphitic carbon nitride (99.7 μmol h−1) is nearly 9.5 times as that of pristine g-C3N4 (10.5 μmol h−1). Such enhancement is attributed to the large specific surface area (91.1 m2 g−1), improved visible-light absorption and efficient separation of photogenerated electrons and holes. The strategy of preparing the porous graphitic carbon nitride with modified melamine as a precursor opens a new gate for the regulation of the morphologies of g-C3N4 to get higher photocatalytic activity.
Co-reporter:Wei-Xin Ouyang, Yu-Xiang Yu and Wei-De Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 22) pp:14827-14835
Publication Date(Web):01 May 2015
DOI:10.1039/C5CP01421B
Advanced materials for electrocatalytic and photoelectrochemical water splitting are key for taking advantage of renewable energy. In this study, ZnO/ZnSe/CdSe/CuxS core–shell nanowire arrays with a nanoporous surface were fabricated via ion exchange and successive ionic layer adsorption and reaction (SILAR) processes. The ZnO/ZnSe/CdSe/CuxS sample displays a high photocurrent density of 12.0 mA cm−2 under AM 1.5G illumination, achieves the highest IPCE value of 89.5% at 500 nm at a bias potential of 0.2 V versus Ag/AgCl, and exhibits greatly improved photostability. The functions of the ZnSe, CdSe, and CuxS layers in the ZnO/ZnSe/CdSe/CuxS heterostructure were clarified. ZnSe is used as a passivation layer to reduce the trapping and recombination of charge carriers at the interfaces of the semiconductors. CdSe functions as a highly efficient visible light absorber and builds heterojunctions with the other components to improve the separation and transportation of the photoinduced electrons and holes. CuxS serves as a passivation layer and an effective p-type hole mediator, which passivates the defects and surface states of the semiconductors and forms p–n junctions with CdSe to promote the hole transportation at the semiconductor–electrolyte interface. The nanoporous surface of the ZnO/ZnSe/CdSe/CuxS core–shell nanowire arrays, together with the tunnel transportation of the charge carriers in the thin films of ZnSe and CdSe, also facilitates the kinetics of photoelectrochemical reactions and improves the optical absorption as well.
Co-reporter:Yao Xu
European Journal of Inorganic Chemistry 2015 Volume 2015( Issue 10) pp:1744-1751
Publication Date(Web):
DOI:10.1002/ejic.201403193
Abstract
Novel composite photocatalysts consisting of CdS and graphitic carbon nitride (CdS/g-C3N4) with different ratios of CdS were prepared. The CdS/g-C3N4 composite photocatalysts were characterized in detail and their photocatalytic activity was evaluated by using rhodamine B and colorless metronidazole as probes. Compared with pure g-C3N4, the CdS/g-C3N4 composite exhibits significantly enhanced photocatalytic activity under visible-light irradiation. More importantly, g-C3N4 substantially reinforces the photostability of CdS nanowires even in a nonsacrificial system. The synergistic effect between CdS and g-C3N4 is found to be primarily responsible for enhancement of the separation of photogenerated electrons and holes, which helps improve the photocatalytic performance. A probable photodegradation process of metronidazole was proposed based on an analysis of the degradation products. This study provides new insight into the preparation of highly efficient and stable sulfide-based composite photocatalysts and facilitates their application in a number of environmentally sensitive areas.
Co-reporter:Si-Zhan Wu, Kui Li, Wei-De Zhang
Applied Surface Science 2015 Volume 324() pp:324-331
Publication Date(Web):1 January 2015
DOI:10.1016/j.apsusc.2014.10.161
Highlights
- •
Novel Ag3VO4/g-C3N4-VN composite photocatalysts were prepared by a simple method.
- •
Ag3VO4/g-C3N4-VN showed high activity toward degradation of RhB.
- •
Ag3VO4/g-C3N4-VN composite with large surface area exhibited excellent stability.
Co-reporter:Liang Xiong;Qing-Shan Shi;Ai-Ping Mai
Polymers for Advanced Technologies 2015 Volume 26( Issue 5) pp:495-501
Publication Date(Web):
DOI:10.1002/pat.3478
Novel waterborne polyurethane (WPU) composites based on NiAl-LDH and ZnO were successfully synthesized by in-situ polymerization. The nanostructured NiAl-LDH/ZnO was first grafted by isophorone diisocyanate (IPDI), forming the NiAl-LDH/ZnO-NCO complex with ―NCO group on the surface, which promotes its homogeneous dispersion in WPU matrix. The microstructure and particle distribution of the composites were characterized. The mechanical properties and the water resistance of the composites were improved. Furthermore, the composites also exhibit significant antibacterial activity towards G(−) Escherichia coli and G(+) Staphylococcus aureus. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Juan Wang, Wei-De Zhang, Wei-Xin Ouyang, Yu-Xiang Yu
Materials Letters 2015 Volume 154() pp:44-46
Publication Date(Web):1 September 2015
DOI:10.1016/j.matlet.2015.04.048
•Hierachically branched structure of ZnO/CuO.•Enhanced photocurrent density and IPCE.•Efficient separation of photogenerated charges.Hierarchically branched ZnO/CuO film was fabricated by a two-step chemical process on Cu foil. CuO nanowires were firstly synthesized on Cu foil by a simple wet chemical method, and then ZnO nanowires were grown on the CuO nanowire scaffold through a hydrothermal process. Comparing with CuO film, the photocurrent response and incident photon to electron conversion efficiency yielded by the hierarchically branched ZnO/CuO film are significantly enhanced under visible light irradiation, which can be attributed to the large contact area with the electrolyte and direct pathways for charge carrier collection. The hierarchical ZnO/CuO thin film could be a promising material for solar energy conversion.
Co-reporter:Peng-Yuan Song, Ming Xu, Wei-De Zhang
Materials Research Bulletin 2015 62() pp: 88-95
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.11.002
Co-reporter:Feng-Yun Su;Yi-Ye Liu
Journal of Solid State Electrochemistry 2015 Volume 19( Issue 8) pp:2321-2330
Publication Date(Web):2015 August
DOI:10.1007/s10008-015-2868-x
Flower-like In2S3 porous films composed of connected ultra-thin curved nanoflakes were prepared on fluorine-doped tin oxide (FTO) substrate by a solvothermal process. The structure and morphology of the In2S3 films were characterized by X-ray diffraction and scanning electron microscopy. The optical properties of the In2S3 films were characterized by UV–vis absorption. The obtained In2S3 films showed n-type semiconductive characteristics and exhibited high anodic photocurrent under visible light illumination. By properly monitoring the experimental conditions, we find that the amount of thiourea, volume ratio of diethylene glycol and deionized water, and reaction time affect the morphology and the photoelectrochemical properties of the In2S3 films. The photocurrent density was achieved from the In2S3 thin film prepared using 3 h, with a transient photocurrent of ca. 1.3 mA cm−2 at the bias potential of +0.2 V vs. RHE.
Co-reporter:Yu-Xiang Yu, Wei-Xin Ouyang, Zhou-Ting Liao, Bin-Bin Du, and Wei-De Zhang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 11) pp:8467
Publication Date(Web):April 23, 2014
DOI:10.1021/am501336u
ZnO/ZnS/CdS/CuInS2 core–shell nanowire arrays with enhanced photoelectrochemical activity under visible light were successfully prepared via ion exchange and hydrothermal methods. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis absorption, X-ray photoemission spectroscopy, and photoelectrochemical response. As a p–n junction photoanode, ZnO/ZnS/CdS/CuInS2 heterostructure shows much higher visible light photoelectrocatalytic activity toward water splitting than ZnO/ZnS/CdS and ZnO/ZnS films. The ZnO/ZnS/CdS/CuInS2 film with optimal constitution exhibits the highest photocurrent of 10.5 mA/cm2 and the highest IPCE of approximately 57.7% at 480 nm and a bias potential of 0 V versus Ag/AgCl. The critical roles of CdS and ZnS in ZnO/ZnS/CdS/CuInS2 heterostructure were investigated. ZnS, as a passivation layer, suppresses the recombination of the photogenerated charge carriers at the interface of the oxide and CuInS2. CdS enhances the absorption of visible light and forms p–n junctions with CuInS2, which promotes the transport of charge carriers and retards the recombination of electrons and holes in CuInS2 to improve the photoelectrochemical performance of ZnO/ZnS/CdS/CuInS2 heterostructure.Keywords: core−shell; photoelectrochemical property; p−n junction; ZnO/ZnS/CdS/CuInS2;
Co-reporter:Yang-Sen Xu, Ze-Jun Zhang and Wei-De Zhang
Dalton Transactions 2014 vol. 43(Issue 9) pp:3660-3668
Publication Date(Web):12 Dec 2013
DOI:10.1039/C3DT53325E
Surface-dispersive-type Bi2O2CO3/Bi2WO6 heterostructured nanosheets were successfully prepared via anion exchange in a hydrothermal process with the graphitic carbon nitride (g-C3N4) as a precursor of CO32−. The Bi2O2CO3 nanoparticles (with diameters about 5 nm) were highly homogeneously dispersed and inlaid in the single-crystalline Bi2WO6 nanosheets. The composites with intimate interfacial contacts between Bi2O2CO3 and Bi2WO6 exhibited superior visible light photocatalytic activity towards the degradation of rhodamine B (RhB). The composite nanosheets containing 7.86 wt% Bi2O2CO3 showed the best performance and the degradation rate of RhB was 6 times faster than that with the bare Bi2WO6. The dramatic enhancement of the photocatalytic activity of the Bi2O2CO3/Bi2WO6 photocatalysts can be attributed to the hetero-interfaces between Bi2O2CO3 and Bi2WO6, their intrinsically layered structure, two-dimensional morphology and the effective separation of the photoinduced carriers at the interfaces and in the semiconductors. This method can be used to design and prepare other Aurivillius heterostructured semiconductors for efficient light harvesting and energy conversion applications.
Co-reporter:Si-Zhan Wu, Cai-Hong Chen, Wei-De Zhang
Chinese Chemical Letters 2014 Volume 25(Issue 9) pp:1247-1251
Publication Date(Web):September 2014
DOI:10.1016/j.cclet.2014.05.017
Graphitic carbon nitride (g-C3N4) with high photocatalytic activity toward degradation of 4-nitrophenol under visible light irradiation was prepared by HCl etching followed by ammonia neutralization. The structure, morphology, surface area, and photocatalytic properties of the prepared samples were studied. After treatment, the size of the g-C3N4 decreased from several micrometers to several hundred nanometers, and the specific area of the g-C3N4 increased from 11.5 m2/g to 115 m2/g. Meanwhile, the photocatalytic activity of g-C3N4 was significantly improved after treatment toward degradation of 4-nitrophenol under visible light irradiation. The degradation rate constant of the small particle g-C3N4 is 5.7 times of that of bulk g-C3N4, which makes it a promising visible light photocatalyst for future applications for water treatment and environmental remediation.A novel acid etching method was developed for processing g-C3N4 with high specific surface area and high photocatalytic performance toward degradation of 4-nitrophenol.
Co-reporter:Si-Zhan Wu, Yu-Xiang Yu, Wei-De Zhang
Materials Science in Semiconductor Processing 2014 Volume 24() pp:15-20
Publication Date(Web):August 2014
DOI:10.1016/j.mssp.2014.02.049
Co-reporter:Peng-Yuan Song, Wei-De Zhang
Materials Research Bulletin 2014 53() pp: 177-184
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.01.036
Co-reporter:Si-Zhan Wu;Na Li
Journal of Porous Materials 2014 Volume 21( Issue 2) pp:157-164
Publication Date(Web):2014 April
DOI:10.1007/s10934-013-9760-9
In this study, ZnO nanoparticles were successfully deposited on the surface of ZnMgAl–CO3–LDHs microspheres to form ZnO/ZnMgAl–CO3–LDHs heterojunction photocatalysts by coprecipitation process. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The results show that ZnO nanoparticles with diameters about 10–80 nm are tightly grown on the nanosheets of the ZnMgAl–CO3–LDHs microspheres. Compared with the pristine ZnMgAl–CO3–LDHs microspheres and pure ZnO, the photocatalytic activity of the heterojunction ZnO/ZnMgAl–CO3–LDHs photocatalyst is significantly enhanced towards the degradation of phenol under UV light irradiation. The enhancement of the photocatalytic activity of the heterojunction catalysts can be ascribed to their improved light absorption property and the lower recombination rate of the photoexcited electrons and holes during the photocatalytic reaction. The optimal molar ratio of ZnO/ZnMgAl–CO3–LDHs for the photocatalysis is 3. The heterojunction photocatalyst ZnO/ZnMgAl–CO3–LDHs may be a promising photocatalyst for future application in water treatment due to its excellent performance in degradation of phenol.
Co-reporter:Yang-Sen Xu and Wei-De Zhang
CrystEngComm 2013 vol. 15(Issue 27) pp:5407-5411
Publication Date(Web):25 Apr 2013
DOI:10.1039/C3CE40172C
A fast and energy-saving anion exchange method for the synthesis of Ag3PO4 microcrystals with various shapes of sphere, rhombic dodecahedron, truncated tetragonal bipyramid microbox and self-assembled parallel quadrilateral prism has been described. The morphology of the Ag3PO4 crystals can be tuned by coordinating Ag+ with various ligands. Thanks to the hollow box structure, the truncated tetragonal bipyramids exhibit higher photocatalytic activity in the degradation of RhB than spherical and rhombic dodecahedral ones under visible light irradiation.
Co-reporter:Yang-Sen Xu and Wei-De Zhang
Dalton Transactions 2013 vol. 42(Issue 4) pp:1094-1101
Publication Date(Web):10 Oct 2012
DOI:10.1039/C2DT31634J
Spherical Bi2MoO6 nanoarchitectures with scale of 500 nm–2 μm were prepared by a solvothermal reaction using bismuth nitrate and ammonium molybdate as precursors. Ag3PO4 nanoparticles were then deposited onto the surface of Bi2MoO6via a facile deposition–precipitation technique. The photocatalytic tests display that the Ag3PO4/Bi2MoO6 nanocomposites possess a much higher rate for degradation of rhodamine B and methylene blue than the pure Ag3PO4 nanoparticles and Bi2MoO6 under visible light. The catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag3PO4. The 50 mol% Ag3PO4-loaded Bi2MoO6 spheres exhibit the highest photocatalytic activity in both the decolorization of RhB and MB. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag3PO4 nanoparticles, and the effective separation of photogenerated carriers at the Ag3PO4/Bi2MoO6 interfaces. In addition, the composite can be easily reclaimed by sedimentation without any loss of its stability. Moreover, the tests of radical scavengers confirmed that h+ and ˙OH were the main reactive species for the degradation of RhB.
Co-reporter:Wen-Hui Zhang, Feng Wang and Wei-De Zhang
Dalton Transactions 2013 vol. 42(Issue 13) pp:4361-4364
Publication Date(Web):05 Feb 2013
DOI:10.1039/C3DT32929A
The effect of Gd3+ doping is harnessed to promote the phase transformation of ultrathin (2 nm) InOOH nanowires to corundum In2O3 and to stabilize the nanowires against morphological deformation. The approach described here suggests a new route toward morphology and phase control of In2O3 nanocrystals, which could be applied to prepare other nanocrystals.
Co-reporter:Wen-Hui Zhang, Wei-De Zhang
Journal of Physics and Chemistry of Solids 2013 Volume 74(Issue 9) pp:1271-1274
Publication Date(Web):September 2013
DOI:10.1016/j.jpcs.2013.04.003
•Corundum nanosheet-based In2O3 microflowers were prepared.•Phase transformation from InOOH to corundum In2O3.•Strong photoluminescence emission.•Triethylene glycol induced self-assembly and transformation process.A new synthesis route for the construction of corundum nanosheet-based In2O3 microflowers is presented in this study. InOOH was firstly prepared by a solvothermal process using In(NO3)3·xH2O as a precursor, urea as a precipitant, and a mixture of triethylene glycol and water as the solvent at 200 °C for 18 h. The corundum nanosheet-based In2O3 microflowers were then obtained by calcining the obtained InOOH at 450 °C under ambient atmosphere. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman and photoluminescence spectroscopy. The effects of solvent and urea on the fabrication of nanosheet-based corundum In2O3 microflowers were investigated and a self-assembly and transformation mechanism is proposed to explain the formation of the hierarchical nanostructures. The corundum nanosheet-based In2O3 microflowers show strong PL emission at 550 nm.
Co-reporter:Wen-Hui Zhang, Wei-De Zhang
Materials Letters 2013 Volume 98() pp:5-7
Publication Date(Web):1 May 2013
DOI:10.1016/j.matlet.2013.01.128
Ultrathin ZnS nanowires with diameter of ca. 1.7 nm and length of ca. 150 nm were synthetized by using a simple, green, and catalyst-free solvothermal process at 140 °C. These as-prepared nanowires were obtained from the reactions between Zn2+ and thiourea by employing oleylamine as a surfactant. The effects of reaction temperature and amount of thiourea on the morphology and size of the ZnS nanowires were studied. The morphology and size of ZnS nanowires can be controlled by varying these experimental conditions. The formation mechanism and optical properties of the nanowires have also been discussed. UV–vis absorption and luminescence emission spectra show that ultrathin ZnS nanowires have strong quantum confinement effect.Highlights► Long ultrathin ZnS nanowires were prepared by a simple, green, catalyst-free method. ► ZnS nanowires can be tuned by varying the reaction conditions. ► Ultrathin ZnS nanowires have strong quantum confinement effect.
Co-reporter:Dr. Yang-Sen Xu ;Dr. Wei-De Zhang
ChemCatChem 2013 Volume 5( Issue 8) pp:2343-2351
Publication Date(Web):
DOI:10.1002/cctc.201300144
Abstract
Ag/AgBr-grafted graphite-like carbon nitride (g-C3N4) is fabricated by the in situ photoreduction of AgBr/g-C3N4 hybrids prepared by a deposition–precipitation method. The Ag/AgBr/g-C3N4 hybrids exhibit a strong absorbance in the visible and near-IR region because of the surface plasmon resonance absorption of Ag nanocrystals. Compared with bare g-C3N4 and Ag/AgBr nanoparticles, a 28-fold and six-fold enhancement in the degradation rate of rhodamine B is observed over Ag/AgBr/g-C3N4 hybrids under visible-light irradiation, respectively. The immense enhancement of the photocatalytic activity is attributed to the extended absorption in the visible-light region, effective charge separation, and synergistic enhancement in the ternary Ag/AgBr/g-C3N4 system. Moreover, the composite can be reclaimed easily by sedimentation without any decrease of its photocatalytic activity. This study provides new insight into the fabrication of highly efficient and stable g-C3N4-based plasmonic photocatalysts and facilitates their practical application to solve environmental issues.
Co-reporter:Dr. Yang-Sen Xu ;Dr. Wei-De Zhang
ChemCatChem 2013 Volume 5( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/cctc.201390041
Co-reporter:Yang-Sen Xu, Ze-Jun Zhang, Wei-De Zhang
Materials Research Bulletin 2013 48(4) pp: 1420-1427
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.12.063
Co-reporter:Dong-Ping Wang;Yue Tang
Microchimica Acta 2013 Volume 180( Issue 13-14) pp:1303-1308
Publication Date(Web):2013 October
DOI:10.1007/s00604-013-1051-2
We have constructed a carbon nitride electrode modified with a bismuth film and show that it can be used for the electroanalysis of lead(II) by differential pulse anodic stripping voltammetry. The combination of such materials is shown to greatly improve the sensing capability of the electrode. Under the optimal conditions, the electrochemical response of the modified electrode is linearly related to the concentration of Pb(II) in the 6 – 1,000 nM concentration range (R = 0.9983). The detection limit is 2.0 pM (at an SNR of 3), and the sensitivity is 8 times better of that of respective graphite electrodes. The sensor enables rapid, highly sensitive, continuous, and environmentally friendly determination of trace levels of Pb(II) at affordable costs.
Co-reporter:Ying Liu, Yu-Xiang Yu, and Wei-De Zhang
The Journal of Physical Chemistry C 2013 Volume 117(Issue 25) pp:12949-12957
Publication Date(Web):May 30, 2013
DOI:10.1021/jp4009652
MoS2/CdS p-n heterojunction films with high photoelectrochemical activity for H2 evolution under visible light were successfully prepared by electrodeposition followed by chemical bath deposition. The films were characterized by X-ray diffraction, scanning electron microscopy, UV–visible absorption, X-ray photoemission spectroscopy, photoluminescence, and photoelectrochemical response. The MoS2/CdS heterostructure shows much higher visible-light photoelectrocatalytic activity and higher stability toward the water splitting than pure CdS film. The MoS2/CdS film with an optimal ratio of 0.14% exhibits the highest photocurrent of 28 mA/cm2 and the highest IPCE of ca. 28% at 420 nm at 0 V vs Ag/AgCl. The critical role of MoS2 in the MoS2/CdS film was investigated. The improved photoelectrochemical performance of the MoS2/CdS heterojunction film was attributed to the visible light absorption enhanced by MoS2 and the formation of a p-n junction between CdS and MoS2, which accelerates the effective separation of photogenerated carriers by the internal electrostatic field in the junction region.
Co-reporter:Ying Liu, Yu-Xiang Yu, Wei-De Zhang
Electrochimica Acta 2012 Volume 59() pp:121-127
Publication Date(Web):1 January 2012
DOI:10.1016/j.electacta.2011.10.051
Ni-doped Fe2O3 thin films which were active photoanodes for water splitting were prepared by electrodeposition. By adjusting Ni molar ratios (Ni/(Ni + Fe)) in the electrolyte, Fe2O3 thin films with various compositions of Ni could be tuned. The films were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, atomic absorption spectrophotometer, and UV–vis spectroscopy. The highest photo-response obtained from Fe2O3 doped with 2.08 mol.% Ni is 1.5 mA/cm2 at 0.65 V vs. Ag/AgCl in 1.0 M NaOH solution. The high performance is attributed to the improvement of charge transport properties and retardation of the charge recombination resulting from the dopants in the lattice. The optical absorption spectra of the films reveal that the bandgaps of the Ni-doped Fe2O3 films are approximately 1.9–2.2 eV for all samples regardless of their doping level. XPS shows that the concentration of Ni is much higher on the surface than that in bulk.Highlights► Ni-doped Fe2O3 thin film active photoanode for water splitting was prepared by electrodeposition. ► The improvement of charge transport properties and retardation of the charge recombination result from the dopants in the lattice. ► The bandgaps of the Ni-doped Fe2O3 films are approximately 1.9–2.2 eV for all samples regardless of their doping level.
Co-reporter:Juan Wang, Wei-De Zhang
Electrochimica Acta 2012 Volume 71() pp:10-16
Publication Date(Web):1 June 2012
DOI:10.1016/j.electacta.2012.03.102
TiO2 nanorod arrays were modified with graphite-like carbon nitride (g-C3N4) by chemical vapor deposition using melamine as a precursor. The prepared g-C3N4/TiO2/FTO was characterized by scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis and photoluminescence spectroscopy for comprehensive morphological, structural, and photoelectrical properties. Electrochemical investigation reveals that modification of TiO2 by g-C3N4 dramatically improves the electron-transfer rate from electrolyte to the electrode surface and the flat band potential of the electrode shifts to a more negative potential with enhanced donor density. The g-C3N4/TiO2/FTO electrode also shows high photoelectrocatalytic activity towards degradation of rhodamine B. Under visible light irradiation, the photocurrent response of the g-C3N4/TiO2/FTO electrode is about 10 times as that of the TiO2/FTO electrode, which makes it a promising nanomaterial for future applications in solar cells, water treatment and photoelectrical devices.Highlights► Vertically aligned TiO2 nanorods were grown on FTO by hydrothermal synthesis. ► The TiO2 nanorods were modified by g-C3N4 to construct g-C3N4/TiO2 heterojunction. ► The photocurrent of the g-C3N4/TiO2/FTO is 10 times as that of the TiO2/FTO. ► High photoelectrocatalytic activity for degradation of Rh B. ► Effective separation of photogenerated electron-hole pairs.
Co-reporter:Ying Liu, Dong-Ping Wang, Yu-Xiang Yu, Wei-De Zhang
International Journal of Hydrogen Energy 2012 Volume 37(Issue 12) pp:9566-9575
Publication Date(Web):June 2012
DOI:10.1016/j.ijhydene.2012.03.118
Functional carbon nanotubes (CNTs) were incorporated into Ti-doped Fe2O3 thin films by a facile, one-step co-electrodeposition method. The films were characterized by X-ray diffraction, scanning electron microscopy, UV–visible absorption, and X-ray photoelectron spectroscopy. The introduction of CNTs results in a better absorption in visible region and greatly enhances the photoelectrochemical properties of the Ti–Fe2O3 films. The improved photoelectrochemical properties of the CNTs and Ti co-doped Fe2O3 films are due to the charge equilibration which interplays between the Ti–Fe2O3 and CNTs. The effect of CNTs to mediate fast charge transfer and to retard charge recombination rate in the composites is also demonstrated by kinetics analysis and electrochemical impedance spectroscopy. The influence of different groups-modified CNTs and different content of CNTs was also studied. The highest photocurrent is 4.5 mA/cm2 at 1.23 V (vs. RHE) obtained by incorporating 0.10 mg/mL amino-group modified CNTs in the Ti–Fe2O3 film. The amino-functionalized CNTs doped film exhibits the highest photoelectric response compared with those doped by the pristine and acid-treated CNTs under the same conditions, which can be ascribed to the better hydrophilicity and dispersibility of the amino-functionalized CNTs.Highlights► CNTs and Ti co-doped Fe2O3 thin film active photoanode for water splitting. ► CNTs enhance the absorption in visible region. ► The amino-functionalized CNTs improve greatly the photoelectrochemical response. ► The CNTs promote the charge transfer and retard charge recombination rate in the composites.
Co-reporter:Wen-Hui Zhang, Wei-De Zhang
Journal of Solid State Chemistry 2012 Volume 186() pp:29-35
Publication Date(Web):February 2012
DOI:10.1016/j.jssc.2011.11.031
Porous nanosheet-based corundum In2O3 microflowers were fabricated by one-pot hydrothermal treatment of d-fructose and In(NO3)3 mixture using urea as a precipitating agent followed by calcination. The products were characterized by X-ray diffraction, scanning and transmission electron microscopy. The effects of d-fructose and urea on the fabrication of nanosheet-based corundum In2O3 microflowers were investigated and a possible mechanism is proposed to explain the formation of the hierarchical nanostructures. The gas sensor based on the In2O3 microflowers exhibits excellent sensing properties for the detection of formaldehyde.Graphical abstractNanosheets-based corundum In2O3 microflowers were fabricated by one-pot hydrothermal treatment of d-fructose/In(NO3)3 mixture followed by calcination, which show high performance for formaldehyde sensing.Highlights► Preparation of porous nanosheet-based corundum In2O3 microflowers. ► Morphology and phase control of In2O3. ► Gas sensor based on the In2O3 microflowers exhibits excellent sensing properties for the detection of formaldehyde.
Co-reporter:Ming-Sheng Gui, Wei-De Zhang
Journal of Physics and Chemistry of Solids 2012 Volume 73(Issue 11) pp:1342-1349
Publication Date(Web):November 2012
DOI:10.1016/j.jpcs.2012.06.009
A hollow-structured heterojunction consisting of Bi2WO6 nanoplatelets and Bi2O3 nanoparticles was successfully prepared by a facile solvothermal process. Bi2O3/Bi2WO6 heterojunction is the aggregate of some hollow spheres with diameter ranging from several hundred nanometers to 1.5 μm and is connected to each other by tube-like cavums. On the basis of scanning and transmission electron microscopy observation and X-ray diffraction analysis of the samples synthesized at different reaction stages, a possible growth mechanism was proposed for the growth of hollow-structured Bi2O3/Bi2WO6 heterojunction. Its photocatalytic activity was evaluated by degradation of rhodamine B under visible-light irradiation (λ>400 nm). The results indicate that the hollow-structured Bi2O3/Bi2WO6 heterojunction exhibits much higher photocatalytic activity than both pure Bi2WO6 and pure Bi2O3. The improved photocatalytic performance can be ascribed to the heterojunction of Bi2O3 and Bi2WO6 in the framework in which the hierarchical hollow structure possesses good permeability and large surface area. More importantly, the hollow-structured Bi2O3/Bi2WO6 heterojunction is not only highly stable but also easy to be separated by simple sedimentation for recycle.Highlights► Hollow-structured Bi2O3/Bi2WO6 heterojunction photocatalysts. ► Micro-droplets serve as soft templates for the formation of the microspheres. ► High visible light photocatalytic performance.
Co-reporter:Yun-Min Zheng, Na Li, Wei-De Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 415() pp:195-201
Publication Date(Web):5 December 2012
DOI:10.1016/j.colsurfa.2012.10.014
In this paper, hierarchical nano/micro-structured Zn–Mg–Al layered double hydroxides (ZnMgAl-LDHs) were successfully synthesized by a one-step urea-method. The morphology, structure, surface area, and adsorption properties of the prepared samples were characterized. The results show that the ZnMgAl-LDHs are of high crystallinity with large surface area, which is favorable for the adsorption. The optimum pH value for the adsorption of methyl orange onto the ZnMgAl-LDHs is 3.0. The adsorption process can be well described by the pseudo-second-order kinetic model. The adsorption isotherm of methyl orange onto the ZnMgAl-LDHs can be depicted by both Freundlich and Langmuir equations, but the latter model matches the results much better than the former one.Graphical abstractThe hierarchical nano/micro-structured Zn–Mg–Al layered double hydroxides show high adsorption property for removing organic pollutants.Highlights► Hierarchical nano/micro-structured Zn–Mg–Al layered double hydroxides were prepared. ► The ZnMgAl-LDHs can effectively adsorb methyl orange. ► The adsorption kinetics of methyl orange follows the pseudo-second-order kinetic model. ► The adsorption isotherm of methyl orange can be depicted by Langmuir equation.
Co-reporter:Liao-Chuan Jiang, Wei-De Zhang, Yu-Xiang Yu, Juan Wang
Electrochemistry Communications 2011 Volume 13(Issue 6) pp:627-630
Publication Date(Web):June 2011
DOI:10.1016/j.elecom.2011.03.029
ZnO nanowires (ZnO-NWs), which were densely grown on multi-walled carbon nanotubes (MWCNTs) arrays, were coated with CdS by successive ionic layer adsorption and reaction. The attained CdS/ZnO-NWs/MWCNTs heterojunction was characterized by scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Electrochemical properties of the CdS/ZnO-NWs/MWCNTs arrays were investigated by electrochemical impedance spectroscopy. The photoelectrochemical response of the CdS/ZnO-NWs/MWCNTs nanocomposite electrode was further studied by amperometry under sunlight irradiation. The CdS/ZnO-NWs/MWCNTs nanocomposite-yielded photocurrent is 2.5 times that of ZnO-NWs/MWCNTs, which is due to the good alignment of the energy bands of CdS and ZnO, thus facilitate the separation of photoinduced electron-hole pairs. In addition, the MWCNTs improve the active surface area and act as electron acceptors, thus promote the interfacial electron-transfer process from the ZnO-NWs to the MWCNTs. The heterojunction arrays of CdS/ZnO-NWs/MWCNTs provide potential applications in the fields of photocatalysis and photoelectrical devices.Research highlights► CdS/ZnO nanowires shell-core structure. ► Heterojunctions based on CdS, ZnO and MWCNTs. ► Efficient separation of photogenerated charge. ► High photocurrent.
Co-reporter:Juan Wang, Wei-De Zhang
Electrochimica Acta 2011 Volume 56(Issue 22) pp:7510-7516
Publication Date(Web):1 September 2011
DOI:10.1016/j.electacta.2011.06.102
CuO nanoplatelets were grown on Cu foils by a one step, template free process. The structure and morphology of the CuO nanoplatelets were characterized by X-ray diffraction, scanning and transmission electron microscopy. The CuO nanoplatelets grown on Cu foil were integrated to be an electrode for glucose sensing. The electrocatalytic activity of the CuO nanoplatelets electrode for glucose in alkaline media was investigated by cyclic voltammetry and chronoamperometry. The electrode exhibits a sensitivity of 3490.7 μA mM−1 cm−2 to glucose which is much higher than that of most reported enzyme-free glucose sensors and the linear range was obtained over a concentration up to 0.80 mM with a detection limit of 0.50 μM (signal/noise = 3). Exhilaratingly, the electrode based on the CuO nanoplatelets is resistant against poisoning by chloride ion, and the interference from the oxidation of common interfering species, such as uric acid, ascorbic acid, dopamine and carbonhydrate compounds, can also be effectively avoided. Finally, the electrode was applied to analyze glucose concentration in human serum samples.Highlights► Adhered growth of CuO nanoplatelets on Cu foils. ► Enzyme-free glucose sensor with very high sensitivity. ► Excellent stability and good anti-interference ability.
Co-reporter:Juan Wang, Wei-De Zhang
Journal of Electroanalytical Chemistry 2011 Volume 654(1–2) pp:79-84
Publication Date(Web):1 May 2011
DOI:10.1016/j.jelechem.2011.01.023
In this study, non-enzymatic detection of uric acid (UA) using a gold nanoparticles-modified vertically aligned multi-walled carbon nanotubes (MWCNTs) electrode is reported. The MWCNTs were coated with Au nanoparticles by magnetron sputtering deposition. The morphology of the Au/MWCNTs nanocomposite was characterized by scanning and transmission electron microscopy. The electrochemical performance of the Au/MWCNTs electrode for detection of uric acid was investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. With amperometric method, at a constant potential of +0.40 V, the sensor exhibits a linear response up to 1.8 mM and sensitivity of 92.19 μA mM−1, the response time is less than 2 s and detection limit is 0.1 μM mM−1 (signal/noise = 3). The Au/MWCNTs nanocomposite electrode also exhibits excellent stability and selectivity against interferences from other electroactive species. Finally, the practical application of the Au/MWCNTs electrode was demonstrated by measuring the concentration of uric acid in human urine samples.Research highlights► Vertically aligned MWCNT arrays coated by Au nanoparticles. ► Detection of uric acid at the Au/MWCNTs electrode. ► High sensitivity and low detection limit. ► Excellent stability and selectivity against interferences.
Co-reporter:Yan-Cui Bai, Wei-De Zhang, Cai-Hong Chen, Jia-Qi Zhang
Journal of Alloys and Compounds 2011 Volume 509(Issue 3) pp:1029-1034
Publication Date(Web):21 January 2011
DOI:10.1016/j.jallcom.2010.09.165
PtAu-alloy nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were successfully prepared by simultaneous reduction of H2PtCl6·6H2O and HAuCl4·3H2O with sodium borohydride as a reducing reagent and sodium citrate as a stabilizing reagent. The morphology and composition of the composite catalyst were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results show that the PtAu alloy nanoparticles with an average diameter of about 3.5 nm and narrow size distribution are supported on MWCNTs. Electrocatalytic oxidation of formic acid at the PtAu/MWCNTs nanocomposite electrode was investigated in a solution containing 0.50 M H2SO4 as a supporting electrolyte and 0.50 M formic acid by cyclic voltammogram and chronoamperometry. The results demonstrate that the PtAu/MWCNTs catalyst exhibits higher activity and stability for electro-oxidation of formic acid than the commercial Pt/C catalyst, reflecting by its lower onset potential (−0.05 V), oxidation mainly occurring in low potential range of −0.05 ± 0.65 V and higher peak current density of 3.12 mA cm−2. The result of CO stripping voltammetry discloses that gold in the PtAu/MWCNTs nanocomposite enhances the catalytic activity and stability.Research highlights▶ Electro-oxidation of HCOOH over PtAu at lower potential, higher peak current. ▶ The stability of the PtAu catalyst is high. ▶ Au in the PtAu catalyst promotes utilization of Pt.
Co-reporter:Mei-Fang Hou, Xiao-Yan Tang, Wei-De Zhang, Lin Liao, and Hong-Fu Wan
Journal of Agricultural and Food Chemistry 2011 Volume 59(Issue 21) pp:11456-11460
Publication Date(Web):October 4, 2011
DOI:10.1021/jf202236c
In this study, polyphenol oxidase (PPO) was extracted from commercial potatoes. Degradation of pentachlorophenol by potato PPO was investigated. The experimental results show that potato PPO is more active in weak acid than in basic condition and that the optimum pH for the reaction is 5.0. The degradation of pentachlorophenol by potato PPO reaches a maximum at 298 K. After reaction for 1 h, the removal of both pentachlorophenol and total organic carbon is >70% with 6.0 units/mL potato PPO at pH 5.0 and 298 K. Pentachlorophenol can be degraded through dechlorination and ring-opening by potato PPO. The work demonstrates that pentachlorophenol can be effectively eliminated by crude potato PPO.
Co-reporter:Xin Xiao and Wei-De Zhang
RSC Advances 2011 vol. 1(Issue 6) pp:1099-1105
Publication Date(Web):15 Sep 2011
DOI:10.1039/C1RA00323B
Bi7O9I3, a fresh member of the bismuth oxyhalide family, with hierarchical micro/nano-architecture is successfully synthesized by a one-step, template and surfactant-free solution method. The as-prepared product was characterized by various techniques. X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis confirm that the composition of the as-fabricated sample is Bi7O9I3. Scanning and transmission electron microscopy observations reveal that the as-synthesized sample exhibits a microsized plate-like structure with dense nanosheets standing on their surfaces. The time-dependent morphology of the Bi7O9I3 sample was investigated, and a possible formation mechanism of the hierarchical structure is proposed. More importantly, the Bi7O9I3 exhibits an excellent photocatalytic activity in the degradation of phenol under visible light irradiation. The high catalytic performance of the Bi7O9I3 hierarchical structure comes from its electronic band structure, high surface area and high surface-to-volume ratio. In addition, the Bi7O9I3 hierarchical architecture is stable during the reaction and can be used repeatedly. The present work not only gives insight into understanding the hierarchical growth behaviour of complex bismuth oxide iodide structures in a solution-phase synthetic system, but also provides a new way to improve the photocatalytic performance by designing desirable structures and morphologies.
Co-reporter:Ming-Sheng Gui, Wei-De Zhang, Qing-Xi Su, Cai-Hong Chen
Journal of Solid State Chemistry 2011 Volume 184(Issue 8) pp:1977-1982
Publication Date(Web):August 2011
DOI:10.1016/j.jssc.2011.05.057
The Bi2O3/Bi2WO6 heterojunction photocatalysts were prepared by a two-step solvothermal process using Bi(NO3)3-ethylene glycol solution as Bi source. The catalysts were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection spectroscopy. The heterostructure catalysts are composed of Bi2O3 nanoparticles as modifier and 3D Bi2WO6 microspheres as substrate. Bi2O3 nanoparticles with diameters of about 10–15 nm are tightly grown on the lateral surface of the Bi2WO6 microspheres. The hierarchical Bi2O3/Bi2WO6 microspheres exhibit higher photocatalytic activity than the single phase Bi2WO6 or Bi2O3 for the degradation of rhodamine B under visible light illumination (λ>420 nm). The enhancement of the photocatalytic activity of the Bi2O3/Bi2WO6 heterojunction catalysts can be ascribed to their improved light absorption property and the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of loading amount of Bi2O3 on the catalytic performance of the heterojunction catalysts was also investigated and the optimal content of Bi2O3 is 3 wt%. The Bi2O3/Bi2WO6 heterojunction photocatalysts are essentially stable during the photocatalytic process.Graphical abstractThe Bi2O3/Bi2WO6 heterojunction catalysts were constructured with improved photocatalytic activity, which can be ascribed to their improved light absorption property and the reduced recombination rate between photoexcited electrons and holes.Highlights► Bi2O3/Bi2WO6 heterojunction photocatalysts. ► Effective separation of photoexcited electrons and holes. ► High visible light photocatalytic activity.
Co-reporter:Jian-Chun Ma
Microchimica Acta 2011 Volume 175( Issue 3-4) pp:309-314
Publication Date(Web):2011 December
DOI:10.1007/s00604-011-0681-5
We report on an electrochemical sensor for the determination of methyl parathion. It is based on an electrode modified with multi-walled carbon nanotubes that were covered with gold nanoparticles (Au-NPs). The vertically aligned array of MWCNTs on a tantalum substrate was coated with Au-NPs by overhead magnetron sputtering deposition. Scanning and transmission electron microscopy and XRD were used to characterize the Au-NP-MWCNTs composite. Cyclic voltammetry and differential pulse voltammetry were employed to evaluate the suitability of the new electrode for the determination of methyl parathion. Under the optimal conditions, the current response of the electrode to methyl parathion is linear in the range from 0.50 to 16.0 mg mL-1, with a detection limit of 50 μg mL-1 (signal/noise = 3), and the sensitivity is 4.5 times better than that of the plain MWCNTs electrode. We conclude that this method represents a simple, rapid, effective and sensitive approach for the detection of methyl parathion.
Co-reporter:Chao Zhang, Weng Weei Tjiu, Tianxi Liu, Wai Yi Lui, In Yee Phang, and Wei-De Zhang
The Journal of Physical Chemistry B 2011 Volume 115(Issue 13) pp:3392-3399
Publication Date(Web):March 15, 2011
DOI:10.1021/jp112284k
Mechanically robust, magnetic nylon-6 nanocomposites reinforced by one-dimensional (1D) carbon nanotube (CNT)−two-dimensional (2D) clay nanoplatelet hybrids have been prepared using a simple melt-compounding technique. The direct iron-catalyzed chemical vapor deposition (CVD) growth of multiwalled CNTs utilizes iron oxide-immobilized clay nanoplatelets as substrates, carrying out in situ intercalation and exfoliation of clay nanoplatelets. By using such a hybridization and coexfoliation method, the as-obtained heterostructured hybrids used without any purification are demonstrated to be ideal and excellent nanofillers for mechanical reinforcement for fabricating nylon-6 nanocomposites, due to their homogeneous dispersion and strong interfacial interaction with the polymer matrix. The nucleation sites provided by the nanohybrids seem to be favorable to the formation of thermodynamically stable α-phase crystals of nylon-6 with much higher stiffness and hardness than γ-form of nylon-6, namely, a silicate-induced crystal transformation from the α-form to the γ-form of nylon-6 was greatly inhibited or “shielded” by the CNT-wrapped clay nanoplatelets. Furthermore, the nanostructured CNT−clay hybrid heterostructures containing residual iron oxide nanoparticles show novel magnetic properties in both bulk solids and polymer nanocomposites. Therefore, this can be probably developed into a facile and practical method to fabricate polymer nanocomposites with high performance and multifunctionality.
Co-reporter:Xin Xiao and Wei-De Zhang
Journal of Materials Chemistry A 2010 vol. 20(Issue 28) pp:5866-5870
Publication Date(Web):09 Jun 2010
DOI:10.1039/C0JM00333F
Self-assembled three-dimensional BiOI microspheres composed of nanoplatelets were synthesized at low temperature using ethanol–water mixed solvent as reaction media and NH3·H2O as pH adjustment. The as-prepared BiOI was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The possible formation mechanism for the architectures was discussed. It was found that mixed solvent and alkali play key roles in the formation of BiOI microspheres. The photocatalytic activity of the as-prepared sample was evaluated by degradation of phenol in aqueous solution under visible light irradiation. The BiOI microspheres show much higher photocatalytic activity than the random BiOI platelets. The total organic carbon measurement after the degradation process indicated that phenol was effectively mineralized over the BiOI microspheres. In addition, the BiOI microspheres are stable during the reaction and can be used repeatedly. The high catalytic performance of the BiOI microspheres comes from their narrow band gap, high surface area and high surface-to-volume ratio.
Co-reporter:Wei-De Zhang, Bin Xu and Liao-Chuan Jiang
Journal of Materials Chemistry A 2010 vol. 20(Issue 31) pp:6383-6391
Publication Date(Web):04 May 2010
DOI:10.1039/B926341A
In this article, we discuss functional hybrid materials based on carbon nanotubes (CNTs) and metal oxides. The unique geometric nanostructure and electrical properties of CNTs significantly promote the dispersion of oxides with strong interaction. The improvement effect of CNTs on the performance of hybrid materials for supercapacitors, lithium ion batteries, electroanalysis and photocatalysis is addressed. The applications of CNT-oxide hybrid materials for solar cell and gas sensors are briefly introduced. The prospects and challenges for material science are also discussed.
Co-reporter:Bin Xu, Min-Ling Ye, Yu-Xiang Yu, Wei-De Zhang
Analytica Chimica Acta 2010 Volume 674(Issue 1) pp:20-26
Publication Date(Web):26 July 2010
DOI:10.1016/j.aca.2010.06.004
In this report, a highly sensitive amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes (MnO2/VACNTs) for determination of hydrogen peroxide (H2O2) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO2/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H2O2 at the MnO2/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO2/VACNTs nanocomposite electrode exhibits a linear dependence (R = 0.998) on the concentration of H2O2 from 1.2 × 10−6 M to 1.8 × 10−3 M, a high sensitivity of 1.08 × 106 μA M−1 cm−2 and a detection limit of 8.0 × 10−7 M (signal/noise = 3). Meanwhile, the MnO2/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and d-(+)-glucose, etc. In addition, the sensor based on the MnO2/VACNTs nanocomposite electrode was applied for the determination of trace of H2O2 in milk with high accuracy, demonstrating its potential for practical application.
Co-reporter:Bin Xu, Wei-De Zhang
Electrochimica Acta 2010 Volume 55(Issue 8) pp:2859-2864
Publication Date(Web):1 March 2010
DOI:10.1016/j.electacta.2009.12.099
In this work, a novel type electrode based on RuO2 nanoparticles-modified vertically aligned carbon nanotubes (RuO2/MWCNTs) was prepared by magnetron sputtering deposition. This RuO2/MWCNTs electrode not only shows a high capacity nature, but also possesses a good response to the pH value. The pH sensor based on the RuO2/MWCNTs nanocomposite electrode exhibits some advantages over the conventional pH sensors. It shows good reproducibility, long-term storage stability (over 1 month) and linear response in the whole pH range (2–12) of Britton–Robinson (B–R) buffer solutions with near-Nernstian response (about −55 mV/pH). The hysteretic widths of the nanocomposite electrode are 6.4 mV, 5.1 mV and 10.2 mV in pH 7–4–7–10–7, pH 7–10–7–4–7 and pH 2–8–12–8–2 loop cycles, respectively. Moreover, the RuO2/MWCNTs electrode displays an excellent anti-interference property and fast response time (less than 40 s). According to the electrochemical impedance measurements, the pH sensing properties of the RuO2/MWCNTs electrode were also discussed.
Co-reporter:Liao-Chuan Jiang, Wei-De Zhang
Electrochimica Acta 2010 Volume 56(Issue 1) pp:406-411
Publication Date(Web):15 December 2010
DOI:10.1016/j.electacta.2010.08.061
The vertically aligned multiwalled carbon nanotube (MWCNT) arrays on tantalum foils were successfully coated with TiO2 nanoparticles by a hydrothermal process. The prepared TiO2/MWCNT hybrid was characterized by scanning electron microscopy and transmission electron microscopy. The charge transfer properties and photocatalytic degradation of rhodamine B with and without bias potential under UV irradiation were investigated. The MWCNTs promoted the separation of photoinduced carriers in the TiO2, thus enhanced photocatalytic activity. Applying bias potential on the photoanode further enhanced its catalytic activity. The efficient charge transportation and high photoelectrocatalytic activity towards degradation of rhodamine B made this hybrid material promising for photocatalyst and for the development of photoelectrical devices.
Co-reporter:Liao-Chuan Jiang, Wei-De Zhang
Biosensors and Bioelectronics 2010 Volume 25(Issue 6) pp:1402-1407
Publication Date(Web):15 February 2010
DOI:10.1016/j.bios.2009.10.038
In this report, a novel type of cupric oxide (CuO) nanoparticles-modified multi-walled carbon nanotubes (MWCNTs) array electrode for sensitive nonenzymatic glucose detection has been fabricated. The morphology of the nanocomposite was characterized by transmission electron microscopy and X-ray diffraction. The electrochemical performance of the CuO/MWCNTs electrode for detection of glucose was investigated by cyclic voltammetry and chronoamperometry. The CuO/MWCNTs electrode showed much higher electrocatalytic activity and lower overvoltage than the bare MWCNTs electrode towards oxidation of glucose. At an applied potential of +0.40 V, the CuO/MWCNTs electrode presented a high sensitivity of 2596 μA mM−1 cm−2 to glucose. In addition, linear range was obtained over a concentration up to 1.2 mM with a detection limit of 0.2 μM (signal/noise = 3). The response time is about 1 s with addition of 0.10 mM glucose. More importantly, the CuO/MWCNTs electrode is also highly resistant against poisoning by chloride ion, and the interference from the oxidation of common interfering species such as ascorbic acid, dopamine, uric acid and carbohydrate compounds is effectively avoided. In addition, the CuO/MWCNTs electrode was also used to analyze glucose concentration in human serum samples. The CuO/MWCNTs electrode exhibits an enhanced electrocatalytic property, low working potential, high sensitivity, excellent selectivity, good stability, and fast amperometric sensing towards oxidation of glucose, thus is promising for the future development of nonenzymatic glucose sensors.
Co-reporter:Wen-Hui Zhang;Jue-Fei Zhou
Journal of Materials Science 2010 Volume 45( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s10853-009-3920-y
In this study, pure ZnO microbullets, ZnO–ZnFe2O4 composite, and ZnO–Fe2O3–ZnFe2O4 composite with micron structured balloons, rods, and particles were prepared by a simple solvent thermal process using methanol or ethanol as solvents. The influence of solvents on the composition and morphology of the products was studied, and their gas-sensing properties were also investigated. The morphology of ZnO microbullets synthesized in ethanol is similar to but more uniform than that of ZnO microbullets synthesized in methanol. The Fe-doped ZnO synthesized in ethanol contains many micron particles homogeneously dispersing on the surface of the microbullets, which is composed of hexagonal wurtzite ZnO and franklinite ZnFe2O4, while Fe-doped ZnO prepared in methanol consists of micron structured balloons, rods, and particles, which is composed of hexagonal wurtzite ZnO, hematite Fe2O3, and franklinite ZnFe2O4. Compared with pure ZnO and ZnO–ZnFe2O4 composite, the ZnO–Fe2O3–ZnFe2O4 composite presented high response, rapid response/recovery characteristics, good selectivity, and excellent stability to acetone at relatively low operating temperature of 190 °C. This sensor could detect acetone in wide range of 1–1000 ppm, which was expected to be a promising gas sensor for detecting acetone.
Co-reporter:Biao Huang;Cai-Hong Chen;Yu-Xiang Yu
Microchimica Acta 2010 Volume 171( Issue 1-2) pp:57-62
Publication Date(Web):2010 October
DOI:10.1007/s00604-010-0408-z
Palladium nanoparticles supported on MWCNTs (Pd/MWCNTs) were successfully prepared by a simple ethylene glycol reduction method in an oil bath. An electrochemical sensor based on Pd/MWCNTs nanocomposite-modified glassy carbon electrode was fabricated for the determination of methyl parathion by differential pulse voltammetry measurement. A highly linear response to methyl parathion in the concentration ranging from 0.10 μg mL−1 to 14 μg mL−1 was observed, and a detection limit of 0.05 μg mL−1 was obtained with the calculation based on signal/noise = 3. The present work provides a simple and rapid approach to the detection of methyl parathion.
Co-reporter:Wei-De Zhang;Jin Chen;Liao-Chuan Jiang;Yu-Xiang Yu;Jia-Qi Zhang
Microchimica Acta 2010 Volume 168( Issue 3-4) pp:259-265
Publication Date(Web):2010 March
DOI:10.1007/s00604-010-0288-2
A highly sensitive and selective glucose biosensor has been constructed by using highly dispersed NiO nanoparticles supported on well-aligned MWCNTs (NiO/MWCNTs) as sensing interface. The NiO/MWCNTs nanocomposite was synthesized by magnetron sputtering deposition of NiO nanoparticles on vertically aligned carbon nanotubes. The nanocomposite electrode showed high electrochemical activity towards the oxidation of glucose in 0.20 M NaOH solution. At an applied potential of +0.50 V, it gives a fast response time (< 5 s) and a linear dependence (R = 0.997) on the glucose concentration up to 7.0 mM with an extraordinarily high sensitivity of 1.77 mA mM-1 cm-2 and a detection limit of 2 μM. The interference by the oxidation of common interfering species such as ascorbic acid, dopamine, uric acid, lactose, and fructose is effectively avoided. The electrode was used to analyze glucose concentration in human serum samples. It allows highly sensitive, stable, and fast amperometric sensing of glucose, which is promising for the development of nonenzymatic glucose sensors.
Co-reporter:Wei-De Zhang, Bin Xu
Electrochemistry Communications 2009 Volume 11(Issue 5) pp:1038-1041
Publication Date(Web):May 2009
DOI:10.1016/j.elecom.2009.03.006
In this communication, a novel solid-state pH sensor based on WO3/MWNTs nanocomposite electrode will be reported. WO3 nanoparticles were homogeneously coated on vertically aligned MWNTs by magnetron sputtering. Potentiometric pH response of the WO3/MWNTs electrode in Britton–Robinson buffers revealed a linear working range from pH 2 to12 with a slope of about −41 mV pH−1 and a response time less than 90 s. The stability of the electrode remained over a month. Moreover, the WO3/MWNTs electrode displayed excellent anti-interference property. Compared to conventional pH sensors, the pH sensor based on WO3/MWNTs nanocomposite electrode also showed excellent reproducibility, high stability and superb selectivity.
Co-reporter:Guang-Quan Mo, Jian-Shan Ye, Wei-De Zhang
Electrochimica Acta 2009 Volume 55(Issue 2) pp:511-515
Publication Date(Web):30 December 2009
DOI:10.1016/j.electacta.2009.09.005
A novel type of ZnO nanowires-modified multiwalled carbon nanotubes (MWCNTs) nanocomposite (ZnO-NWs/MWCNTs) has been prepared by a hydrothermal process. The ZnO-NWs/MWCNTs nanocomposite has a uniform surface distribution and large coverage of ZnO nanowires onto MWCNTs with 3D configuration, which was characterized by scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy methods were applied to investigate the electrochemical properties of ZnO-NWs/MWCNTs nanocomposite. Surprisingly, unlike the conventional n-type semiconducting ZnO nanowires grown on Ta substrate, the ZnO-NWs/MWCNTs nanocomposite exhibits excellent electron transfer capability and gives a pair of well-defined symmetric redox peaks towards ferricyanide probe. What's more, the ZnO-NWs/MWCNTs nanocomposite shows remarkable electrocatalytic activity (current response increased 4 folds at 0.3 V) towards H2O2 by comparing with bare MWCNTs. The ZnO-NWs/MWCNTs nanocomposite could find applications in novel biosensors and other electronic devices.
Co-reporter:Xue-Yong Ma, Wei-De Zhang
Polymer Degradation and Stability 2009 Volume 94(Issue 7) pp:1103-1109
Publication Date(Web):July 2009
DOI:10.1016/j.polymdegradstab.2009.03.024
A novel waterborne polyurethane/flower-like ZnO nanowhiskers (WPU/f-ZnO) composite with different f-ZnO content (0–4.0 wt%) was synthesized by an in-situ copolymerization process. The f-ZnO consisting of uniform nanorods was prepared via a simple hydrothermal method. In order to disperse and incorporate f-ZnO into WPU matrix, f-ZnO was modified with γ-aminopropyltriethoxysilane. Morphology of f-ZnO in WPU matrix was characterized by scanning electron microscope. The properties of WPU/f-ZnO composites such as mechanical strength, thermal stability as well as water swelling were strongly influenced by the f-ZnO contents. It was demonstrated that appropriate amount of f-ZnO with good dispersion in the WPU matrix significantly improved the performance of the composites. The mechanical property was enhanced with an increase of f-ZnO content up to the optimum content (1 wt%) and then declined. Incorporation of f-ZnO enhanced the water resistance of the composites remarkably. It was amazing to observe that the thermal degradation temperatures of the composites initially decreased significantly and then leveled off with content increase of f-ZnO, which was different from the results of other WPU composite systems reported. Antibacterial activity of WPU/f-ZnO composite films against Escherichia coli and Staphylococcus aureus was also tested. The results revealed that the antibacterial activity enhanced with the increasing f-ZnO content, and the best antibacterial activity was obtained at the loading level of 4.0 wt% f-ZnO.
Co-reporter:Cai-Xia Zhao;Dong-Cheng Sun
Polymer Composites 2009 Volume 30( Issue 5) pp:649-654
Publication Date(Web):
DOI:10.1002/pc.20609
Abstract
Waterborne polyurethane (WBPU) and multiwalled carbon nanotubes (CNTs) composite films with 0–4.0 wt% CNTs were prepared by ultrasonic dispersion of carboxylic acid-functionalized CNTs in WBPU followed by emulsion casting process. The elongations at break of the WBPU/CNTs composites increase with the incorporation of CNTs. The tensile strength and crystallinity of the nanocomposite films with lower CNTs contents (<2 wt%) increase obviously; while the tensile strengths of the composites with more CNTs (≥2 wt%) decrease, in contrast to the pure PU film. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that the CNTs are uniformly dispersed in the composites incorporated with lower CNTs contents (≤1.5 wt%). However, aggregation of CNTs increased with increasing CNTs content in the WBPU/CNTs composites, causing the macrophase separation. The dispersion state of the CNTs affects the crystallinity of the PU matrix and the phase separation of the composites, which are two key factors to influence the mechanical properties of the WBPU/CNTs composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Co-reporter:Jian-Shan Ye;Yan-Cui Bai
Microchimica Acta 2009 Volume 165( Issue 3-4) pp:361-366
Publication Date(Web):2009 June
DOI:10.1007/s00604-009-0143-5
A novel type of palladium nanoparticles-modified multiwalled carbon nanotubes composite-electrode with electrocatalytic activity for oxygen reduction is presented. The nanocomposite was prepared by magnetron sputtering deposition with Pd in Ar atmosphere on MWNTs, which were synthesized on Ta plates by chemical vapor deposition. Both scanning electron microscopy and transmission electron microscopy were employed to observe the surface morphology. The Pd nanoparticles, with diameters around 5 nm, are dispersed at the tips and on the sidewalls of the MWNTs. Voltammetry, amperometry and electrochemical impedance measurements were used to demonstrate the strong electrocatalytic activity of the nanocomposite in acid solution. Compared to the bare MWNT electrode, the PdNPs/MWNT nanocomposite shows a positive shift of the O2 reduction current at onset potentials from +400 to +500 mV, a concurrent 1.5-fold increase in the O2 reduction peak current with high stability. The successful preparation of PdNPs/MWNTs nanocomposite by magnetron sputtering deposition opens a new path for an efficient dispersion of promising nanoparticles for fuel cells and O2 sensors.
Co-reporter:Wei-De Zhang, Liao-Chuan Jiang and Jian-Shan Ye
The Journal of Physical Chemistry C 2009 Volume 113(Issue 36) pp:16247-16253
Publication Date(Web):August 14, 2009
DOI:10.1021/jp905500n
ZnO nanowires (ZnO-NWs) were adhesively grown on multiwalled carbon nanotubes (MWCNTs) arrays by a hydrothermal process. Electrochemical properties of the electrode based on the ZnO-NWs/MWCNTs nanocomposite were investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The photoelectrochemical responses of the ZnO-NWs/MWCNTs nanocomposite electrode were further studied by linear sweep voltammetry and amperometry under sunlight or UV light irradiation. Compared with pure ZnO-NWs on tantalum substrate, the charge transfer rate of the ZnO-NWs/MWCNTs nanocomposite was remarkably increased because of the MWCNTs. A Mott−Schottky plot displayed a high donor density of 3.9 × 1019 cm−3, a flat band potential of −0.8 V, and a space charge layer of 7 nm. In addition, the ZnO-NWs/MWCNTs nanocomposite yielded higher photocurrent than pure ZnO-NWs. The decay constant of the ZnO-NWs/MWCNTs nanocomposite was also lower than that of its pure counterpart. The recombination of photoinduced electron−hole pairs in the ZnO-NWs/MWCNTs heterojunction was hindered, thus enhancing the photoelectrical conversion efficiency. The heterojunction of ZnO-NWs/MWCNTs provides potential applications in the field of photocatalysis and photoelectrical devices.
Co-reporter:Qian-Jing Ruan and Wei-De Zhang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 10) pp:4168-4173
Publication Date(Web):2017-2-22
DOI:10.1021/jp810098f
Orthorhombic Bi2Fe4O9 microplatelets and nanosheets were successfully synthesized through a rather facile hydrothermal process. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and UV−vis absorption spectra. The photocatalytic activity of the as-prepared samples was evaluated by the degradation of methyl orange under UV and visible irradiation. The Bi2Fe4O9 nanosheets showed high photocatalytic activity toward methyl orange degradation under visible and UV irradiation, while the Bi2Fe4O9 microplatelets were active only under UV irradiation.
Co-reporter:Qian-Jing Ruan, Wei-De Zhang
Materials Letters 2008 Volume 62(Issue 27) pp:4303-4305
Publication Date(Web):31 October 2008
DOI:10.1016/j.matlet.2008.07.012
La-Bi-Fe-O nanorods were prepared for the first time via a facile hydrothermal method without any surfactant. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the structure and morphology of the material. The semiconductive La-Bi-Fe-O nanorods are mainly composed of orthorhombic Bi2Fe4O9 and a small amount of orthorhombic La1.08Bi0.92O3.03. The gas sensing properties of the sensor based on La-Bi-Fe-O nanorods were studied and the nanorods exhibited a p-type behavior. Both the sensitivity and selectivity of the sensor towards formaldehyde were very high, and the sensor could be used to detect formaldehyde as low concentration as 5 ppm. More importantly, the operation temperature of the La-Bi-Fe-O sensor was low. This would be very significant in applications, such as detecting and preventing indoor formaldehyde pollution.
Co-reporter:Wen-Hui Zhang, Wei-De Zhang
Sensors and Actuators B: Chemical 2008 Volume 134(Issue 2) pp:403-408
Publication Date(Web):25 September 2008
DOI:10.1016/j.snb.2008.05.015
SnO2 nanoparticles and ZnO microrods were prepared and characterized by X-ray diffraction (XRD) and a field emission scanning electron microscope (FESEM). The results showed that the mean grain size of the SnO2 nanoparticles was 40 nm; the diameter of ZnO microrods was about 1–1.5 μm with a length between 8 and 10 μm. The gas-sensing properties of the SnO2 nanoparticles, ZnO microrods and the nanocomposite of SnO2 nanoparticles doped with 5–15 wt% ZnO microrods were investigated. The gas-sensing properties of the SnO2 nanoparticles were greatly improved by doping with the ZnO microrods. The SnO2–ZnO nanocomposite sensor showed high and quick response to trimethylamine (TMA) at 190–330 °C. This sensor showed the advantages of high selectivity, excellent sensitivity, strong stability and prompt response/recovery characteristics in detecting TMA at 330 °C. It could be used to detect the freshness of fishes.
Co-reporter:Lei Zhou;WeiDe Zhang;HuanFeng Jiang
Science China Chemistry 2008 Volume 51( Issue 3) pp:241-247
Publication Date(Web):2008 March
DOI:10.1007/s11426-008-0030-7
A facile and efficient method for the synthesis of tetrasubstituted olefins in supercritical carbon dioxide was developed by using carbon nanotubes-supported palladium nanoparticles (Pd/CNTs) as the catalyst. Compared with common Pd/C, Pd/CNTs could more effectively catalyze the reaction of dibromo-substituted olefins with boronic acids, affording the corresponding tetrasubstituted olefins with moderate to good yields. This environmentally benign route with an easy-to-handle catalyst provides an appealing alternative to the currently available methods.
Co-reporter:Tianxi Liu, Yuejin Tong, Wei-De Zhang
Composites Science and Technology 2007 Volume 67(3–4) pp:406-412
Publication Date(Web):March 2007
DOI:10.1016/j.compscitech.2006.09.007
Multi-walled carbon nanotube (MWCNT)/polyetherimide (PEI) nanocomposite films have been prepared by casting and imidization. A homogeneous dispersion of MWCNTs throughout the PEI matrix is observed by scanning electron microscopy of fracture surfaces, which shows not only a fine dispersion of MWCNTs but also strong interfacial adhesion with the matrix, as evidenced by the presence of many broken but strongly embedded carbon nanotubes (CNTs) in the matrix and by the absence of debonding of CNTs from the matrix. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperature of PEI increases by about 10 °C by the addition of 1 wt% MWCNTs. Mechanical testing shows that for the addition of 1 wt% MWCNTs, the elastic moduli of the nanocomposites are significantly improved by about 250% while the tensile strength is comparable to that of the matrix. This improvement is due to the strong interfacial interaction between the MWCNTs and the PEI matrix which favors stress transfer from the polymer to the CNTs.
Co-reporter:Hong Wang, Wei-De Zhang, Lun-Yu Zhu, Ming-Cai Chen
Solid State Ionics 2007 Volume 178(1–2) pp:131-136
Publication Date(Web):31 January 2007
DOI:10.1016/j.ssi.2006.10.028
LiFePO4 coating on LiCoO2 with a thickness ranging 10–100 nm improved the electrochemical performance of the cathode material at high temperature and high potential. At 60 °C and at a rate of 1 C, 5.0 wt.% LiFePO4-coated LiCoO2 showed better capacity retention (132 mAh/g) with 4.2 V charge-cutoff after 250 cycles, while the bare cathode (pure LiCoO2) showed 5% capacity retention under the same conditions after only 150 cycles. When cycled at 60 and 75 °C, the amount of Co dissolution from LiCoO2 was greatly reduced in the LiFePO4-coated cathode material. The coating layer of LiFePO4 not only protects the LiCoO2 but also serves as an active cathode material with good conductivity. The LiFePO4-coated LiCoO2 could be a high performance cathode material for Li-ion battery.
Co-reporter:I. Y. Phang;T. X. Liu;W.-D. Zhang
Advanced Materials 2006 Volume 18(Issue 1) pp:73-77
Publication Date(Web):15 NOV 2005
DOI:10.1002/adma.200501217
High-performance composites are produced using nanostructured clay–carbon nanotube (CNT) hybrids as a reinforcing filler. The intercalation of iron particles between the clay platelets serves as the catalyst for the growth of CNTs, while the platelets are exfoliated by the CNTs, forming the unique 3D nanostructured hybrid filler: a 2D clay platelet with several attached 1D CNTs (see Figure). The clay–CNTs hybrid can be directly incorporated into nylon-6 by simple melt compounding.
Co-reporter:Hui-Li Xu, Wei-De Zhang
Chinese Chemical Letters (January 2017) Volume 28(Issue 1) pp:
Publication Date(Web):January 2017
DOI:10.1016/j.cclet.2016.10.008
In this study, a new facile preparation method of nanocomposites consisting of graphene oxide and manganese dioxide nanowires (GO/MnO2 NWs) was developed. The morphology, structure and composition of the resulted products were characterized by transmission electron microscopy, X-ray diffraction and N2 adsorption and desorption. The GO/MnO2 nanocomposite was used as an electrode material for non-enzymatic determination of hydrogen peroxide. The proposed sensor exhibits excellent electrocatalytic performance for the determination of hydrogen peroxide in phosphate buffer solution (PBS, pH 7) at an applied potential of 0.75 V. The non-enzymatic biosensor for determination of hydrogen peroxide displayed a wide linear range of 4.90 μmol L−1–4.50 mmol L−1 with a correlation coefficient of 0.9992, a low detection limit of 0.48 μmol L−1 and a high sensitivity of 191.22 μA (mmol L−1)−1 cm−2 (signal/noise, S/N = 3). Moreover, the non-enzymatic biosensor shows an excellent selectivity.A GO/MnO2 nanocomposite electrode consisting of graphene oxide and mesoporous manganese dioxide displays excellent electrocatalytic performance for determination of hydrogen peroxide with low detection limit, high sensitivity and stability.
Co-reporter:Cheng-Qun Xu, Kui Li, Wei-De Zhang
Journal of Colloid and Interface Science (1 June 2017) Volume 495() pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.jcis.2017.01.111
Nitrogen-deficient graphitic carbon nitride (CN-HAc) was synthesized by thermal condensation of acetic acid-treated melamine as a precursor. The nitrogen vacancies play a remarkable role on controlling the electronic structure of g-C3N4, such as extending the optical absorption and enhancing the separation efficiency of photogenerated charge carriers, resulting in the improvement of photocatalytic activity. The photocatalytic activity of the catalysts was evaluated by splitting water and degradation of rhodamine B (RhB) under visible light irradiation (λ > 420 nm). The average H2 evolution rate on CN-HAc is 24 μmol h−1, which is about 5 times of that on pristine g-C3N4. Meanwhile, CN-HAc exhibits superior photocatalytic mineralization of RhB. The possible formation mechanism of nitrogen-deficient in the framework of g-C3N4 is proposed.Nitrogen-deficient graphitic carbon nitride (CN-HAc) was synthesized by thermal condensation of acetic acid-treated melamine as a precursor. The obtained photocatalysts display high and stable activity for photocatalytic degradation of rhodamine B and generation of hydrogen through water splitting.
Co-reporter:Xin Xiao and Wei-De Zhang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 28) pp:NaN5870-5870
Publication Date(Web):2010/06/09
DOI:10.1039/C0JM00333F
Self-assembled three-dimensional BiOI microspheres composed of nanoplatelets were synthesized at low temperature using ethanol–water mixed solvent as reaction media and NH3·H2O as pH adjustment. The as-prepared BiOI was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The possible formation mechanism for the architectures was discussed. It was found that mixed solvent and alkali play key roles in the formation of BiOI microspheres. The photocatalytic activity of the as-prepared sample was evaluated by degradation of phenol in aqueous solution under visible light irradiation. The BiOI microspheres show much higher photocatalytic activity than the random BiOI platelets. The total organic carbon measurement after the degradation process indicated that phenol was effectively mineralized over the BiOI microspheres. In addition, the BiOI microspheres are stable during the reaction and can be used repeatedly. The high catalytic performance of the BiOI microspheres comes from their narrow band gap, high surface area and high surface-to-volume ratio.
Co-reporter:Wei-De Zhang, Bin Xu and Liao-Chuan Jiang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 31) pp:NaN6391-6391
Publication Date(Web):2010/05/04
DOI:10.1039/B926341A
In this article, we discuss functional hybrid materials based on carbon nanotubes (CNTs) and metal oxides. The unique geometric nanostructure and electrical properties of CNTs significantly promote the dispersion of oxides with strong interaction. The improvement effect of CNTs on the performance of hybrid materials for supercapacitors, lithium ion batteries, electroanalysis and photocatalysis is addressed. The applications of CNT-oxide hybrid materials for solar cell and gas sensors are briefly introduced. The prospects and challenges for material science are also discussed.
Co-reporter:Wei-Xin Ouyang, Yu-Xiang Yu and Wei-De Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 22) pp:NaN14835-14835
Publication Date(Web):2015/05/01
DOI:10.1039/C5CP01421B
Advanced materials for electrocatalytic and photoelectrochemical water splitting are key for taking advantage of renewable energy. In this study, ZnO/ZnSe/CdSe/CuxS core–shell nanowire arrays with a nanoporous surface were fabricated via ion exchange and successive ionic layer adsorption and reaction (SILAR) processes. The ZnO/ZnSe/CdSe/CuxS sample displays a high photocurrent density of 12.0 mA cm−2 under AM 1.5G illumination, achieves the highest IPCE value of 89.5% at 500 nm at a bias potential of 0.2 V versus Ag/AgCl, and exhibits greatly improved photostability. The functions of the ZnSe, CdSe, and CuxS layers in the ZnO/ZnSe/CdSe/CuxS heterostructure were clarified. ZnSe is used as a passivation layer to reduce the trapping and recombination of charge carriers at the interfaces of the semiconductors. CdSe functions as a highly efficient visible light absorber and builds heterojunctions with the other components to improve the separation and transportation of the photoinduced electrons and holes. CuxS serves as a passivation layer and an effective p-type hole mediator, which passivates the defects and surface states of the semiconductors and forms p–n junctions with CdSe to promote the hole transportation at the semiconductor–electrolyte interface. The nanoporous surface of the ZnO/ZnSe/CdSe/CuxS core–shell nanowire arrays, together with the tunnel transportation of the charge carriers in the thin films of ZnSe and CdSe, also facilitates the kinetics of photoelectrochemical reactions and improves the optical absorption as well.
Co-reporter:Yang-Sen Xu, Ze-Jun Zhang and Wei-De Zhang
Dalton Transactions 2014 - vol. 43(Issue 9) pp:NaN3668-3668
Publication Date(Web):2013/12/12
DOI:10.1039/C3DT53325E
Surface-dispersive-type Bi2O2CO3/Bi2WO6 heterostructured nanosheets were successfully prepared via anion exchange in a hydrothermal process with the graphitic carbon nitride (g-C3N4) as a precursor of CO32−. The Bi2O2CO3 nanoparticles (with diameters about 5 nm) were highly homogeneously dispersed and inlaid in the single-crystalline Bi2WO6 nanosheets. The composites with intimate interfacial contacts between Bi2O2CO3 and Bi2WO6 exhibited superior visible light photocatalytic activity towards the degradation of rhodamine B (RhB). The composite nanosheets containing 7.86 wt% Bi2O2CO3 showed the best performance and the degradation rate of RhB was 6 times faster than that with the bare Bi2WO6. The dramatic enhancement of the photocatalytic activity of the Bi2O2CO3/Bi2WO6 photocatalysts can be attributed to the hetero-interfaces between Bi2O2CO3 and Bi2WO6, their intrinsically layered structure, two-dimensional morphology and the effective separation of the photoinduced carriers at the interfaces and in the semiconductors. This method can be used to design and prepare other Aurivillius heterostructured semiconductors for efficient light harvesting and energy conversion applications.
Co-reporter:Wen-Hui Zhang, Feng Wang and Wei-De Zhang
Dalton Transactions 2013 - vol. 42(Issue 13) pp:NaN4364-4364
Publication Date(Web):2013/02/05
DOI:10.1039/C3DT32929A
The effect of Gd3+ doping is harnessed to promote the phase transformation of ultrathin (2 nm) InOOH nanowires to corundum In2O3 and to stabilize the nanowires against morphological deformation. The approach described here suggests a new route toward morphology and phase control of In2O3 nanocrystals, which could be applied to prepare other nanocrystals.
Co-reporter:Yang-Sen Xu and Wei-De Zhang
Dalton Transactions 2013 - vol. 42(Issue 4) pp:NaN1101-1101
Publication Date(Web):2012/10/10
DOI:10.1039/C2DT31634J
Spherical Bi2MoO6 nanoarchitectures with scale of 500 nm–2 μm were prepared by a solvothermal reaction using bismuth nitrate and ammonium molybdate as precursors. Ag3PO4 nanoparticles were then deposited onto the surface of Bi2MoO6via a facile deposition–precipitation technique. The photocatalytic tests display that the Ag3PO4/Bi2MoO6 nanocomposites possess a much higher rate for degradation of rhodamine B and methylene blue than the pure Ag3PO4 nanoparticles and Bi2MoO6 under visible light. The catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag3PO4. The 50 mol% Ag3PO4-loaded Bi2MoO6 spheres exhibit the highest photocatalytic activity in both the decolorization of RhB and MB. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag3PO4 nanoparticles, and the effective separation of photogenerated carriers at the Ag3PO4/Bi2MoO6 interfaces. In addition, the composite can be easily reclaimed by sedimentation without any loss of its stability. Moreover, the tests of radical scavengers confirmed that h+ and ˙OH were the main reactive species for the degradation of RhB.
