Co-reporter:Larissa Thia;Mingshi Xie;Donghwan Kim
Catalysis Science & Technology (2011-Present) 2017 vol. 7(Issue 4) pp:874-881
Publication Date(Web):2017/02/20
DOI:10.1039/C6CY02580C
Formic acid and its salts are important chemical intermediates. Industrial production of formic acid involves liquid phase carbonylation of methanol to methyl formate followed by hydrolysis to formic acid. Alternatively, formic acid can be generated during glycerol electro-oxidation when glycerol undergoes C–C bond cleavage. Silver based catalysts such as carbon supported silver–gold alloys significantly improve selectivity to formic acid during glycerol electro-oxidation. However, these catalysts tend to suffer from poor electro-chemical activity. Herein, we examined the ability of Ag containing, porous Au structures to tune the glycerol oxidation pathway towards formate and glycolate whilst maintaining high electro-catalytic activity. Our catalyst consisted of an Au rich porous framework that possessed residual amounts of Ag within its pores. When tested for glycerol electro-oxidation, the Ag containing porous Au catalyst exhibited both high selectivity towards formate and high electrochemical activity.
Co-reporter:Zhenchao Lei;Weiming Feng;Chunhua Feng;Weijia Zhou;Chaohai Wei
Journal of Materials Chemistry A 2017 vol. 5(Issue 5) pp:2012-2020
Publication Date(Web):2017/01/31
DOI:10.1039/C6TA09887H
The handling of a huge amount of sludge produced from industrial wastewater treatment plants is a critical issue. We report a facile and cost-effective pyrolysis approach to transform coke wastewater sludge flocs into valuable carbon materials that show the potential of being used in energy-storage devices and fuel cells. The nitrified sludge flocs are naturally rich in carbon, nitrogen, sulfur, and other inorganic particles and thus are attractive precursors for producing N,S dual-doped carbon with a hierarchical mesoporous graphene-like structure via the simple one-step pyrolysis method without the addition of external N- and/or S-containing organic compounds, chemical activation agents, or graphitization catalyst precursors. Owing to its unique features, the resulting nitrified sludge floc derived carbon (NSFC) exhibits outstanding capacitive performance. The specific capacitance determined in 1 M H2SO4 at a current density of 1 A g−1 is 889 F g−1, the highest among reported values for carbon-based materials in inorganic electrolytes, as far as we are aware. The NSFC also shows an excellent cycling stability with only 1.2% loss in capacitance after 10 000 cycles at a current density of 20 A g−1. The NSFC also achieves superior activity towards the oxygen reduction reaction (ORR) and proves to be a promising metal-free ORR electrocatalyst showing comparable electrocatalytic performance, higher selectivity, and longer durability as compared to the commercial Pt/C benchmark.
Co-reporter:Yizhong Lu 逯一中;Larissa Thia;Adrian Fisher;Chi-Young Jung
Science China Materials 2017 Volume 60( Issue 11) pp:1109-1120
Publication Date(Web):28 April 2017
DOI:10.1007/s40843-017-9029-5
Controlling the surface structure and composition at the atomic level is an effective way to tune the catalytic properties of bimetallic catalysts. Herein, we demonstrate a generalized strategy to synthesize highly monodisperse, surfactant-free octahedral PtxNi1−x nanoparticles with tunable surface structure and composition. With increasing the Ni content in the bulk composition, the degree of concaveness of the octahedral PtxNi1−x nanoparticles increases. We systematically studied the correlation between their surface structure/composition and their observed oxygen reduction activity. Electrochemical studies have shown that all the octahedral PtxNi1−x nanoparticles exhibit enhanced oxygen reduction activity relative to the state-of-the-art commercial Pt/C catalyst. More importantly, we find that the surface structure and composition of the octahedral PtxNi1−x nanoparticles have significant effect on their oxygen reduction activity. Among the studied PtxNi1−x nanoparticles, the octahedral Pt1Ni1 nanoparticles with slight concaveness in its (111) facet show the highest activity. At 0.90 V vs. RHE, the Pt mass and specific activity of the octahedral Pt1Ni1 nanoparticles are 7.0 and 7.5-fold higher than that of commercial Pt/C catalyst, respectively. The present work not only provides a generalized strategy to synthesize highly monodisperse, surfactant-free octahedral PtxNi1−x nanoparticles with tunable surface structure and composition, but also provides insights to the structure-activity correlation.双金属催化材料的催化性质可以通过在原子水平下控制材料的表面结构和组成进行有效调节. 本文发展了一种普适性的方法合成 具有高度分散性、洁净表面和可调的表面结构和组成的PtxNi1−x八面体纳米粒子. 研究发现在反应过程中, 通过增加Ni前驱体的含量, 合成 的PtxNi1−x八面体纳米粒子的(111)晶面的凹陷程度逐渐加大. 我们系统研究了PtxNi1−x八面体纳米粒子的表面结构或组成与其氧还原电催化 活性之间的相互关系. 电化学研究结果表明所有的PtxNi1−x八面体纳米粒子均表现出比标准商业Pt/C催化剂更高的氧还原活性. 更重要的 是, 我们发现PtxNi1−x八面体纳米粒子的表面结构和组成对其氧还原电催化活性具有很大的影响. 研究发现, 具有轻微(111)晶面凹陷程度的 Pt1Ni1八面体纳米粒子显示出最高的氧还原电催化活性. 在0.9 V(相对于标准氢电极)电势条件下, Pt1Ni1八面体纳米粒子的氧还原质量活性 和面积活性分别为标准商业Pt/C催化剂的7.0和7.5倍. 该研究不仅提供了一种普适性的方法合成具有高度分散性、洁净表面和可调的表面 结构和组成的PtxNi1−x八面体纳米粒子, 同时可为理解催化材料的结构-性质相互关系规律提供指导.
Co-reporter:Yizhong Lu;Jiong Wang;Yuecheng Peng;Adrian Fisher
Advanced Energy Materials 2017 Volume 7(Issue 21) pp:
Publication Date(Web):2017/11/01
DOI:10.1002/aenm.201700919
AbstractA highly efficient and durable electrocatalyst of Pd hydride nanocubes encapsulated within 2D amorphous Ni-B nanosheets is reported. The PdH0.43 nanocubes are first synthesized via a simple N,N-dimethylformamide thermal treatment. The as-synthesized PdH0.43 nanocubes are then encapsulated in 2D amorphous NiB nanosheets by NaBH4 reduction in the presence of nickel species. During the NaBH4 treatment, the PdH0.43 can be further transformed into PdH0.706 due to the presence of endogenous H2. Electrochemical studies demonstrate that the degree of hydride of Pd nanocubes (PdHx) plays an important role in the enhancement of their oxygen reduction reaction (ORR) activity. With increasing x value, both the activity and stability increase significantly. At 0.90 V versus reversible hydrogen electrode, the ORR activity of PdH0.706 @Ni-B reaches 1.05 A mgPd−1, which is nearly five times higher than that of the state-of-the-art Pt catalysts. Accelerated durability tests show that even after 10 000 potential cycles, there is negligible shift in their half-wave potential and no shape and structure change occurs, indicating the incorporation of amorphous 2D Ni-B nanosheets can greatly improve their stability without compromising their activity. The present study illustrates the importance of high degree of hydride and presence of amorphous Ni-B nanosheets on the enhancement of ORR activity for Pd-based electrocatalyst.
Co-reporter:Ming Shi Xie, Bao Yu Xia, Yawei Li, Ya Yan, Yanhui Yang, Qiang Sun, Siew Hwa Chan, Adrian Fisher and Xin Wang
Energy & Environmental Science 2016 vol. 9(Issue 5) pp:1687-1695
Publication Date(Web):21 Jan 2016
DOI:10.1039/C5EE03694A
Electroreduction of carbon dioxide to hydrocarbons has been proposed as a promising way to utilize CO2 and maintain carbon balance in the environment. Copper (Cu) is an effective electrocatalyst for such a purpose. However, the overall selectivity towards hydrocarbons on Cu-based electrodes is still very limited. In this work, we develop a general amino acid modification approach on Cu electrodes for the selective electroreduction of CO2 towards hydrocarbons. A remarkable enhancement in hydrocarbon generation is achieved on these modified copper electrodes, regardless of the morphology of the Cu electrodes. A density functional theory calculation reveals that the key intermediate CHO* is stabilized by interacting with –NH3+ of the adsorbed zwitterionic glycine. Our results suggest that amino acids and their derivatives are promising modifiers in improving the selectivity of hydrocarbons in CO2 electroreduction.
Co-reporter:Le Yu;Bao Yu Xia;Xiong Wen Lou
Advanced Materials 2016 Volume 28( Issue 1) pp:92-97
Publication Date(Web):
DOI:10.1002/adma.201504024
Co-reporter:Ya Yan, Bin Zhao, Sung Chul Yi and Xin Wang
Journal of Materials Chemistry A 2016 vol. 4(Issue 33) pp:13005-13010
Publication Date(Web):28 Jul 2016
DOI:10.1039/C6TA05317C
Electrocatalytic water splitting is a promising means for clean energy production. There is a great need to develop low cost, efficient and durable electrocatalysts for such purposes. Herein, we report a novel hierarchical nanostructure composed of FeP porous nanorods on CNT backbones. The directed growth of α-FeO(OH) nanospindles on CNTs was first realized via a bottom-up assembly, followed by phosphorization transformation. When evaluated for the electrocatalytic water splitting reaction, these hierarchical structures exhibited superior oxygen evolution performance due to their advantageous structural features.
Co-reporter:Le Tao, Mingshi Xie, Geraldine Giap Ying Chiew, Zhijuan Wang, Wei Ning Chen and Xin Wang
Chemical Communications 2016 vol. 52(Issue 37) pp:6292-6295
Publication Date(Web):07 Apr 2016
DOI:10.1039/C6CC00976J
A novel nondestructive strategy of improving electron trans-inner membrane movements in bioelectrocatalysts is realized by overexpressing NADH dehydrogenase II in the inner membrane. A microbial fuel cell loaded with these improved bioelectrocatalysts shows significantly enhanced performance based on promoting the utilization of intracellular primary electron donors in bioelectrocatalysts.
Co-reporter:Zhijun Jia, Jun Wang, Yi Wang, Bingyang Li, Baoguo Wang, Tao Qi, Xin Wang
Journal of Materials Science & Technology 2016 Volume 32(Issue 2) pp:147-152
Publication Date(Web):February 2016
DOI:10.1016/j.jmst.2015.08.003
Birnessite-type MnO2 (δ-MnO2) nano-sheets were successfully synthesized by an interfacial synthesis method in this work. The properties and electrochemical performance of the as-prepared δ-MnO2 were analyzed and evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption measurement and electrochemical tests. This facile synthesis method enables δ-MnO2 nano-sheets to show a large specific surface area (257.5 m2 g−1). The electrochemical test results show that the specific capacitance is 272 F g−1 and the specific capacitance retention is over 96.7% after 1000 cycles at a scan rate of 10 mV s−1. All results demonstrate that δ-MnO2 has a great potential application in high-performance electrochemical capacitors, and this interfacial synthesis method will be a very promising method to synthesize highly active MnO2 materials in a large scale.
Co-reporter:Peng Xiao;Wei Chen
Advanced Energy Materials 2015 Volume 5( Issue 24) pp:
Publication Date(Web):
DOI:10.1002/aenm.201500985
Hydrogen evolution by means of electrocatalytic water-splitting is pivotal for efficient and economical production of hydrogen, which relies on the development of inexpensive, highly active catalysts. In addition to sulfides, the search for non-noble metal catalysts has been mainly directed at phosphides due to the superb activity of phosphides for hydrogen evolution reaction (HER) and their low-cost considering the abundance of the non-noble constituents of phosphides. Here, recent research focusing on phosphides is summarized based on their synthetic methodology. A comparative study of the catalytic activity of different phosphides towards HER is then conducted. The catalytic activity is evaluated by overpotentials at fixed current density, Tafel slope, turnover frequency, and the Gibbs free energy of hydrogen adsorption. Based on the methods discussed, perspectives for the various methods of phosphides synthesis are given, and the origins of the high activity and the role of phosphorus on the improved activity towards HER are discussed.
Co-reporter:Peng Xiao;Xiaoming Ge;Haibo Wang;Zhaolin Liu;Adrian Fisher
Advanced Functional Materials 2015 Volume 25( Issue 10) pp:1520-1526
Publication Date(Web):
DOI:10.1002/adfm.201403633
Development of nonnoble metal catalysts for hydrogen evolution reaction (HER) is critical to enable an efficient production of hydrogen at low cost and large scale. In this work, a novel bimetallic carbide nanostructure consisting of Mo2C and WC is synthesized. Based on a highly conductive WC backbone, nanosized Mo2C particles are integrated onto WC, forming a well-defined and highly robust nanowire structure. More importantly, it is found that electrochemical activation can partially remove surface carbon and activate the catalyst by changing its surface hydrophilicity. As a result, the residual carbon contributes positively to the activity, besides its role of protecting carbide from oxidation. Benefiting from the structure, the catalyst achieves high activity, stable electrolysis towards HER.
Co-reporter:Haibo Wang, Larissa Thia, Nan Li, Xiaoming Ge, Zhaolin Liu, and Xin Wang
ACS Catalysis 2015 Volume 5(Issue 6) pp:3174
Publication Date(Web):April 17, 2015
DOI:10.1021/acscatal.5b00183
A hybrid support consisting of carbon nitride and graphene (CNx/G) is prepared by annealing polypyrrole/GO at 800 °C. Pd nanoparticles (NPs) are then loaded onto the support by a microwave–polyol method. Pd-CNx/G is used as a catalyst for glycerol electro-oxidation in 0.5 M NaOH aqueous solution. Electrochemical characterization and product analysis by high-performance liquid chromatography show that, in comparison to Pd NPs supported on carbon black, Pd NPs on a support containing nitrogen atoms has the ability to promote selectivity toward C3 products as well as increase activity. The main factors influencing the selectivity and activity are also discussed.Keywords: carbon nitride; glycerol oxidation; graphene; Pd nanoparticle; selectivity
Co-reporter:Ya Yan, BaoYu Xia, Nan Li, Zhichuan Xu, Adrian Fisher and Xin Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 1) pp:131-135
Publication Date(Web):07 Nov 2014
DOI:10.1039/C4TA04858J
The development of non-noble-metal based hydrogen-evolving catalysts is essential to the practical application of water-splitting devices. Improvement of both the activity and stability of such catalysts remains a key challenge. In this work, a simple solvothermal method is developed to directly grow MoS2 and WS2 on carbon cloth with vertically oriented nanosheet layers. With the unique layer orientation that maximally exposes active edge sites as well as a rapid release of small gas bubbles to maintain a large working area, such prepared 3-dimensional electrodes exhibit high activity towards the HER. In addition, they also exhibit prominent electrochemical durability, thanks to the strong bonding between the nanosheet layers and the substrate along with the self-removal of the as-formed H2 bubbles from the nano-porous electrode surface.
Co-reporter:Le Tao, Haibo Wang, Mingshi Xie, Larissa Thia, Wei Ning Chen and Xin Wang
Chemical Communications 2015 vol. 51(Issue 61) pp:12170-12173
Publication Date(Web):22 May 2015
DOI:10.1039/C5CC03188E
A novel design of a microbial fuel cell is realized by constructing bio-cocatalyst beads immobilized with riboflavin-secreting Escherichia coli and decoupling them from an anodic biocatalyst. A microbial fuel cell loaded with these bio-cocatalyst beads shows significantly enhanced performance without occupying an active electrode surface area.
Co-reporter:Ya Yan;Larissa Thia;Bao Yu Xia;Xiaoming Ge;Zhaolin Liu;Adrian Fisher
Advanced Science 2015 Volume 2( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/advs.201500120
Co-reporter:Nan Li, Hai-Bo Wang, Larissa Thia, Jing-Yuan Wang and Xin Wang
Analyst 2015 vol. 140(Issue 2) pp:449-455
Publication Date(Web):18 Nov 2014
DOI:10.1039/C4AN01900H
Dopamine (DA) has attracted extensive interest due to not only its important roles in physiological and pathological processes, but also its prospective applications in chemistry and materials science. In this work, we demonstrate that the urease catalytic reaction is an effective new approach for a better control of DA polymerization to polydopamine nanoparticles (PDA NPs). And we further develop an original and novel method for sensitive and visual sensing of urea through spectroscopic or particle size analysis. The detection is based on DA polymerization to PDA NPs that can be controlled by the reaction rate of urease-catalyzed urea hydrolysis, correspondingly, correlated with the varied urea concentration. The composition, morphologies and sizes of the resulting PDA NPs are characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dynamic light scattering (DLS) spectroscopy, respectively. Under optimal reaction conditions, the UV absorbance of DA polymerization at 400 nm shows a good response towards urea detection over a range of 1 × 10−7 to 1 × 10−3 M with a limit of detection (LOD) of 100 nM (S/N = 3). Moreover, the sizes of the resulting PDA NPs increase linearly with urea concentration from 5 × 10−6 to 1 × 10−4 M. The newly developed assay allows the enzymatic-reaction driven PDA NPs to be used for quantitative detection of urea with many advantages, e.g. simple preparation, easy visualization, good sensitivity, wide detection range and low interference, in particular, no complex sensor-fabrication required.
Co-reporter:Dr. Ya Yan;Dr. Bao Yu Xia;Dr. Xiaoming Ge; Zhaolin Liu;Dr. Adrian Fisher; Xin Wang
Chemistry - A European Journal 2015 Volume 21( Issue 50) pp:18062-18067
Publication Date(Web):
DOI:10.1002/chem.201503777
Abstract
The design of cheap and efficient water splitting systems for sustainable hydrogen production has attracted increasing attention. A flexible electrode, based on carbon cloth substrate and iron phosphide nanotubes coated with an iron oxide/phosphate layer, is shown to catalyze overall water splitting. The as-prepared flexible electrode demonstrates remarkable electrocatalytic activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at modest overpotentials. The surface iron oxide/phosphate, which is formed in situ, is proposed to improve the HER activity by facilitating the water-dissociation step and serves directly as the catalytically-active component for the OER process.
Co-reporter:Lei Zhang, Hao Bin Wu, Ya Yan, Xin Wang and Xiong Wen (David) Lou
Energy & Environmental Science 2014 vol. 7(Issue 10) pp:3302-3306
Publication Date(Web):04 Aug 2014
DOI:10.1039/C4EE01932F
Hierarchical MoS2 microboxes constructed by ultrathin nanosheets are synthesized by a facile template-assisted strategy. The first step involves the L-cysteine assisted uniform growth of hierarchical MoS2 nanosheets on MnCO3 microcube templates which are at the same time converted to MnS. Hierarchical MoS2 microboxes can be obtained by selectively dissolving MnS through acid washing. When evaluated as an anode material for lithium-ion batteries, the hierarchical MoS2 microboxes manifest high specific capacity and excellent cycling performance. The hierarchical MoS2 microboxes also show enhanced electrocatalytic activity for electrochemical hydrogen evolution from water.
Co-reporter:Peng Xiao, Mahasin Alam Sk, Larissa Thia, Xiaoming Ge, Rern Jern Lim, Jing-Yuan Wang, Kok Hwa Lim and Xin Wang
Energy & Environmental Science 2014 vol. 7(Issue 8) pp:2624-2629
Publication Date(Web):29 May 2014
DOI:10.1039/C4EE00957F
Electrochemical production of hydrogen from water has been directed to the search for non-noble metal based and earth-abundant catalysts. In this work, we propose a novel cost-effective catalyst, molybdenum phosphide that exhibits high activity towards the hydrogen evolution reaction (HER) in both acid and alkaline media even in bulk form. Comparative analysis of Mo, Mo3P and MoP as catalysts for HER clearly indicates that phosphorization can potentially modify the properties of the metal and different degrees of phosphorization lead to distinct activities and stabilities. Theoretical calculations by density functional theory also show that a simple phosphorization of molybdenum to form MoP introduces a good ‘H delivery’ system which attains nearly zero binding to H at a certain H coverage. With the combination of experimental results and theoretical calculations, this work has enlightened a new way of exploring cost-effective catalysts for HER.
Co-reporter:BaoYu Xia, Ya Yan, Xin Wang and Xiong Wen (David) Lou
Materials Horizons 2014 vol. 1(Issue 4) pp:379-399
Publication Date(Web):31 Mar 2014
DOI:10.1039/C4MH00040D
Graphene-based hybrid nanostructures have attracted increasing interest worldwide. Benefiting from their remarkable electrochemical catalytic properties derived from chemical compositions and synergetic effects of multi-functionalities, these graphene-based hybrid nanomaterials will play a significant role in cutting-edge innovation for novel electrocatalysts. In this review, we summarize recent progress in the design and synthesis of graphene-based hybrid nanomaterials with controlled shape, size, composition and structure, and their application as efficient electrocatalysts for energy related systems. We conclude this article with some future trends and prospects which are highlighted for further investigations on graphene-based nanomaterials as advanced electrocatalysts.
Co-reporter:Ya Yan, BaoYu Xia, Zhichuan Xu, and Xin Wang
ACS Catalysis 2014 Volume 4(Issue 6) pp:1693
Publication Date(Web):April 17, 2014
DOI:10.1021/cs500070x
Hydrogen is expected to play a major role in the development of sustainable energy and environment. Electrocatalytic hydrogen evolution reaction (HER) is known as an efficient method for large-scale hydrogen production, and in this electrochemical process, efficient and low-cost electrocatalysts are indispensable. Recent advances have revealed that nanostructured molybdenum sulfides (MoSx) would be promising alternatives to Pt for the electrochemical generation of hydrogen from water. In this review, we focus on the recent progress on MoSx-based materials as electrocatalysts toward the HER under acidic condition. Moreover, future research scope and important challenges emerging from MoSx nanostructures are discussed toward the development of more advanced and efficient electrocatalysts for HER.Keywords: activity; electrocatalysts; hydrogen evolution reaction; molybdenum sulfides; nanostructures; stability
Co-reporter:Nan Li, Larissa Thia and Xin Wang
Chemical Communications 2014 vol. 50(Issue 30) pp:4003-4006
Publication Date(Web):18 Feb 2014
DOI:10.1039/C4CC00412D
A specific bifunctional molecule containing amidine is prepared to construct a CO2-responsive surface via molecular self-assembly. The smart surface undergoes CO2-responsive switching of surface charges and wettability, leading to distinctively selective adsorption of hydrophobic/hydrophilic molecules.
Co-reporter:Peng Xiao, Xiaoming Ge, Zhaolin Liu, Jing-Yuan Wang, Xin Wang
Journal of Alloys and Compounds 2014 Volume 587() pp:326-331
Publication Date(Web):25 February 2014
DOI:10.1016/j.jallcom.2013.10.187
•The effect of calcium incorporation in strontium molybdate is investigated.•Metallic molybdenum ex-solution is observed under SOFCs’ operating condition.•Molybdenum ex-solution is demonstrated to be reversible.•Molybdenum ex-solution enhances the electrochemical performance.Calcium is incorporated into strontium molybdate to form Sr1−xCaxMoO3 as an electronic conductor for solid oxide fuel cells (SOFCs). Metallic molybdenum was observed with the increasing content of Ca substitution for Sr in Sr1−xCaxMoO3. Rietveld refinement reveals the phase transition from cubic to tetragonal perovskite structure, which implies its decreased thermodynamic stability under reducing conditions with increasing content of Ca. X-ray diffraction (XRD) and differential scanning calorimetry-thermo-gravimetric analysis (DSC-TGA) further prove that this Mo ex-solution is reversible. The electrochemical performances of Sr1−xCaxMoO3 towards H2 and CH4 oxidation at 800 °C are examined. The performance is improved in H2 atmosphere with the introduction of Ca, 330 mW cm−2 of Sr0.5Ca0.5MoO3–Gd0.2Ce0.8O1.9 (GDC) vs. 280 mW cm−2 of SrMoO3–GDC, which can be ascribed to the segregated Mo as the additional catalyst. However, carbon deposition is observed after exposure to CH4 at 800 °C for both Sr0.7Ca0.3MoO3–GDC and Sr0.5Ca0.5MoO3–GDC, in contrast to the absence of carbon on SrMoO3–GDC.
Co-reporter:Haibo Wang, Mingshi Xie, Larissa Thia, Adrian Fisher, and Xin Wang
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 1) pp:119-125
Publication Date(Web):December 11, 2013
DOI:10.1021/jz402416a
Substitutional nitrogen doping in graphene has been a very powerful tool to tailor the pristine property of graphene and furthermore extend its application. While nitrogen-doped graphene (N-graphene) has shown many potential applications in catalysis, electronics, sensors and so on, there is still a lack of accurate control of substitutional nitrogen doping, and higher performance toward various applications is always needed. This Perspective summarizes the ongoing developments toward better control of nitrogen doping. Moreover, two recent strategies aiming to promote the activity of N-graphene are also discussed.
Co-reporter:Tian Wu;Hui Ming Zhou;Dr. Bao Yu Xia;Peng Xiao;Ya Yan;Ming Shi Xie;Dr. Xin Wang
ChemCatChem 2014 Volume 6( Issue 6) pp:1538-1542
Publication Date(Web):
DOI:10.1002/cctc.201400058
Abstract
Pt nanostructures are intensively studied for many environmental and energy applications. Their synthesis normally involves capping agents/organic species or the assistance of templates/substrates, making the preparation process complicated. Therefore, it is still challenging to obtain Pt nanostructures with clean surface through a one-step surfactant-free method. We report herein the preparation of 3 D Pt nanodendrites with clean surface by a facile inorganic species assisted strategy. The possible specific adsorption of iron and nitrate ions would assist the growth of this 3 D Pt nanostructure. Thanks to its unique 3 D morphology composed of interconnected 1 D Pt nanorods/wires, the unsupported 3 D Pt nanodendrites exhibit higher stability and activity than commercial carbon black supported Pt nanoparticles and Pt black electrocatalysts for the oxygen reduction reaction and oxidation of small fuel molecules.
Co-reporter:Nan Li, Ya Yan, Bao-Yu Xia, Jing-Yuan Wang, Xin Wang
Biosensors and Bioelectronics 2014 Volume 54() pp:521-527
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.040
•Intrinsic peroxidase-like activity of the unique nanorod-structured tungsten carbide (WC NRs) was observed.•A simple, low cost and sensitive colorimetric method is proposed to detect H2O2 with a limit of detection 60 nM.•The as-prepared WC NRs exhibit high robustness of catalytic activity at high temperature (100 °С), in acidic media (pH=2) and organic media.•The WC NRs as peroxidase mimic is easy recovered with good reusability.•The WC NRs also possess good peroxidase activity in different organic solvents investigated (acetonitrile, isopropanol and methanol).Tungsten carbide nanorods (WC NRs) are demonstrated for the first time to possess intrinsic peroxidase-like activity towards typical peroxidase substrates, such as 3, 3', 5, 5'-tetramethylbenzidine (TMB) and ο-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2). The reactions catalyzed by these nanorods follow the Michaelis–Menten kinetics. The excellent catalytic performance of WC NRs could be attributed to their intrinsic catalytic activity to efficiently accelerate the electron-transfer process and facilitate the decomposition of H2O2 to generate more numbers of reactive oxygen species (ROS). Based upon the strong peroxidase-like activity of these WC NRs, a colorimetric sensor for H2O2 is designed, which provides good response towards H2O2 concentration over a range of 2×10−7–8×10−5 M with a detection limit of 60 nM. Moreover, the peroxidase-like activities of WC NRs with TMB as the substrate are investigated in both protic and aprotic organic media, showing different colorimetric reactions from that performed in aqueous solutions. In comparison with the natural horse radish peroxidase, WC NR exhibits excellent robustness of catalytic activity and considerable reusability, thus making it a promising mimic of peroxidase catalysts.Tungsten carbide nanorods have been demonstrated for the first time to possess intrinsic peroxidase-like activity to catalytically oxidize the peroxidase substrates in the presence of H2O2 in both aqueous and organic media. The colorimetric reactions in organic media are different with that performed in aqueous solutions. Based on the peroxidase-like properties of these WC NRs, a colorimetric sensor for H2O2 is designed. With high activity, remarkable stability and considerable reusability, tungsten carbide nanorods would be a promising peroxidase mimic.
Co-reporter:Bao Yu Xia ; Hao Bin Wu ; Ya Yan ; Xiong Wen (David) Lou
Journal of the American Chemical Society 2013 Volume 135(Issue 25) pp:9480-9485
Publication Date(Web):June 6, 2013
DOI:10.1021/ja402955t
Ultrathin one-dimensional (1D) nanostructures such as nanowires and nanorods have drawn considerable attention due to their promising applications in various fields. Despite the numerous reports on 1D nanostructures of noble metals, one-pot solution synthesis of Pt 1D nanostructures still remains a great challenge, probably because of the intrinsic isotropic crystal growth behavior of Pt. Herein, we demonstrate the facile solvothermal synthesis of nanowire assemblies composed of ultrathin (ca. 3 nm) and ultralong (up to 10 μm) Pt nanowires without involving any template. The oriented attachment mechanism is found to be partially responsible for the formation of such ultrathin Pt nanowires. The amine molecules generated during the reaction might assist the formation of nanowire assemblies. Importantly, the present system can be extended to synthesize Pt-based alloy nanowire assemblies such as Pt–Au and Pt–Pd. These Pt nanowires can be easily cast into a free-standing membrane, which exhibits excellent electrocatalytic activity and very high stability for formic acid and methanol oxidation and the oxygen reduction reaction.
Co-reporter:Yi Wang, Huili Liu, Li Wang, Haibo Wang, Xuan Du, Fang Wang, Tao Qi, Jong-Min Lee and Xin Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 23) pp:6839-6848
Publication Date(Web):04 Apr 2013
DOI:10.1039/C3TA10214A
A large-area three-dimensional (3D) reduced graphene oxide (TRGO) material was obtained by facile heat treatment of a two-dimensional (2D) reduced graphene oxide (RGO) material. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption results reveal that the new material is composed of small and fluffy graphene nanosheets, with many graphene arrays as well as 3D interconnected macropores and mesopores in some local positions, and possesses an ultrahigh specific surface area (>1000 m2 g−1) and large pore volume. The material was used to support a Pd catalyst for formic acid electrooxidation, demonstrating a much better electrocatalytic activity in terms of the onset potential and peak current density (seven times larger) than that of conventional carbon black, the most popular catalyst support. To tailor the electronic properties, the TRGO material was further functionalized with chitosan (CS). Compared to the Pd loaded on TRGO, Pd nanoparticles supported on the CS-functionalized TRGO show a better catalytic activity and good stability. This work provides a promising catalyst support material for direct formic acid fuel cells.
Co-reporter:Ya Yan, Baoyu Xia, Xiaoying Qi, Haibo Wang, Rong Xu, Jing-Yuan Wang, Hua Zhang and Xin Wang
Chemical Communications 2013 vol. 49(Issue 43) pp:4884-4886
Publication Date(Web):13 Mar 2013
DOI:10.1039/C3CC41031E
A novel electrocatalyst of layered MoS2 supported on reduced graphene oxide (RGO) decorated with nano-sized tungsten carbide (WC) shows an enhanced catalytic performance in the hydrogen evolution reaction, which could be attributed to the presence of a conductive and electrocatalytically-active nano-WC dispersant and the positive synergistic effect between nano-WC/RGO and layered MoS2.
Co-reporter:Ya Yan, BaoYu Xia, Xiaoming Ge, Zhaolin Liu, Jing-Yuan Wang, and Xin Wang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 24) pp:12794
Publication Date(Web):December 3, 2013
DOI:10.1021/am404843b
Well-defined ultrathin MoS2 nanoplates are developed by a facile solvent-dependent control route from single-source precursor for the first time. The obtained ultrathin nanoplate with a thickness of ∼5 nm features high density of basal edges and abundant unsaturated active S atoms. The multistage growth process is investigated and the formation mechanism is proposed. Ultrathin MoS2 nanoplates exhibit an excellent activity for hydrogen evolution reaction (HER) with a small onset potential of 0.09 V, a low Tafel slope of 53 mV dec–1, and remarkable stability. This work successfully demonstrates that the introduction of unsaturated active S atoms into ultrathin MoS2 nanoplates for enhanced electrocatalytic properties is feasible through a facial one-step solvent control method, and that this may open up a potential way for designing more efficient MoS2-based catalysts for HER.Keywords: electrocatalyst; hydrogen evolution reaction; hydrothermal synthesis; MoS2 nanoplates; solvent-dependent control; unsaturated sulfur atoms;
Co-reporter:Dr. Bao Yu Xia;Hao Bin Wu; Xin Wang; Xiong Wen (David) Lou
Angewandte Chemie International Edition 2013 Volume 52( Issue 47) pp:12337-12340
Publication Date(Web):
DOI:10.1002/anie.201307518
Co-reporter:Dr. Bao Yu Xia;Hao Bin Wu; Xin Wang; Xiong Wen (David) Lou
Angewandte Chemie 2013 Volume 125( Issue 47) pp:12563-12566
Publication Date(Web):
DOI:10.1002/ange.201307518
Co-reporter:Haibo Wang, Baoyu Xia, Ya Yan, Nan Li, Jing-Yuan Wang, and Xin Wang
The Journal of Physical Chemistry B 2013 Volume 117(Issue 18) pp:5606-5613
Publication Date(Web):April 10, 2013
DOI:10.1021/jp401418z
In this paper, we obtained various water-soluble polymer functionalized graphene in dimethyl sulfoxide under ultrasonication. The atomic force microscope analysis and control experiment shows the water-soluble polymer is the crucial part to help solvent molecules separate interlayer. Such polymer/graphene exhibits high conductivity and tunable surface property, as confirmed by the selected area electron diffraction and Raman and electrochemical impedance spectroscopy. As a result, a catalyst based on polyvinyl pyrrolidone (PVP)/graphene shows better methanol oxidation performance than that based on PVP/reduced graphene oxide. By changing to another polymer, poly(4-vinylpyridine)/graphene shows a stable and reversible response to pH, and demonstrates its potential for sensor application.
Co-reporter:Haibo Wang, Thandavarayan Maiyalagan, and Xin Wang
ACS Catalysis 2012 Volume 2(Issue 5) pp:781
Publication Date(Web):March 16, 2012
DOI:10.1021/cs200652y
Nitrogen doping has been an effective way to tailor the properties of graphene and render its potential use for various applications. Three common bonding configurations are normally obtained when doping nitrogen into the graphene: pyridinic N, pyrrolic N, and graphitic N. This paper reviews nitrogen-doped graphene, including various synthesis methods to introduce N doping and various characterization techniques for the examination of various N bonding configurations. Potential applications of N-graphene are also reviewed on the basis of experimental and theoretical studies.Keywords: electrocatalysis; energy storage; field-effect transistor; graphene; nitrogen doping;
Co-reporter:Mingzhu Liu, Ya Yan, Lan Zhang, Xin Wang and Cheng Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 23) pp:11458-11461
Publication Date(Web):20 Apr 2012
DOI:10.1039/C2JM31484C
Deflated-balloon-like and crumpled carbon nanosheets were prepared via a low-temperature hydrothermal carbonization of glucose at the two-phase interfaces. A low amount of glucose and a high amount of sodium dodecyl sulfate were found to be propitious to the formation of graphitic carbon nanosheets with low thickness. Their applications as supercapacitive materials were demonstrated.
Co-reporter:Thandavarayan Maiyalagan, Xiaochen Dong, Peng Chen and Xin Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 12) pp:5286-5290
Publication Date(Web):13 Feb 2012
DOI:10.1039/C2JM16541D
A three-dimensional interconnected graphene monolith was used as an electrode support for pulsed electrochemical deposition of platinum (Pt) nanoparticles. Pt nanoparticles with well-defined morphology and small size can be obtained by controlling electrodeposition potential and time. Electrochemical characterization was carried out to examine the electrocatalytic activity of this monolithic electrode towards methanol oxidation in acidic media. The results show that the carbon material surface and structure have a strong influence on the Pt particle size and morphology. Compared with the three-dimensional scaffold of carbon fibers, the three-dimensional graphene when used as a free-standing electrode support resulted in much improved catalytic activity for methanol oxidation in fuel cells due to its three-dimensionally interconnected seamless porous structure, high surface area and high conductivity.
Co-reporter:Bao Yu Xia, Bao Wang, Hao Bin Wu, Zhaolin Liu, Xin Wang and Xiong Wen (David) Lou
Journal of Materials Chemistry A 2012 vol. 22(Issue 32) pp:16499-16505
Publication Date(Web):26 Jun 2012
DOI:10.1039/C2JM32816J
The practical application of low temperature fuel cells is largely hindered by the unavailability of efficient electrocatalysts with high activity and stability. A promising strategy to design highly active electrocatalysts is to use multicomponent catalysts including alloyed active metals and metal oxides as the support. In this paper, we develop highly efficient and stable sandwich-structured TiO2–Pt–G(graphene) hybrid electrocatalysts. Structural characterization and electrochemical measurements indicate that these TiO2–Pt–G hybrid electrocatalysts have much higher activity and stability compared to conventional carbon black supported Pt electrocatalysts. The significantly enhanced electrochemical performance is ascribed to the unique sandwich sheet-like structure that is responsible for the strong metal–support interaction and the proposed synergetic effect. These findings suggest that such TiO2–Pt–G hybrid electrocatalysts are promising for use in low temperature fuel cells.
Co-reporter:Bao Yu Xia, Hao Bin Wu, Jun Song Chen, Zhiyu Wang, Xin Wang and Xiong Wen (David) Lou
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 2) pp:473-476
Publication Date(Web):17 Nov 2011
DOI:10.1039/C1CP23367J
TiO2
nanoparticles-decorated graphene nanosheets have been prepared by a facile hydrothermal method. After depositing Pt nanoparticles exclusively around the interface between TiO2 and rGO, the obtained Pt/TiO2@rGO electrocatalyst exhibits remarkably enhanced electrocatalytic performance, which could be attributed to the unique structure and some possible synergetic effect from the 3-phase Pt–TiO2–rGO junctions.
Co-reporter:Bao Yu Xia, Shujiang Ding, Hao Bin Wu, Xin Wang and Xiong Wen (David)
RSC Advances 2012 vol. 2(Issue 3) pp:792-796
Publication Date(Web):29 Nov 2011
DOI:10.1039/C1RA00587A
High-stability Pt electrocatalysts have been prepared using hierarchical CNT@TiO2 structures composed of TiO2 nanosheets grafted on the CNT backbone as the support. The as-prepared Pt/CNT@TiO2 electrocatalysts manifest high electrocatalytic activity with greatly improved stability compared to conventional CNT or carbon black supported Pt electrocatalysts.
Co-reporter:Peng Xiao, Xiaoming Ge, Lan Zhang, Jong-Min Lee, Jing-Yuan Wang, Xin Wang
International Journal of Hydrogen Energy 2012 Volume 37(Issue 23) pp:18349-18356
Publication Date(Web):December 2012
DOI:10.1016/j.ijhydene.2012.08.131
Strontium molybdate (SrMoO3) as an electronic conductor was incorporated with yttria-stabilized zirconia (YSZ) to form an anode scaffold for solid oxide fuel cells. Gd0.2Ce0.8O1.9 (GDC) nanoparticles were introduced by wet impregnation to complete the Ni-free GDC infiltrated SrMoO3–YSZ anode fabrication. The effects of SrMoO3 on the electrode conductivity and GDC infiltration on the catalytic activity were examined. A pronounced performance improvement was observed both on wet H2 and CH4 oxidation for the 56 wt.% GDC infiltrated SrMoO3–YSZ. In particular, the polarization resistance decreased from 8 Ω cm2 to 0.5 Ω cm2 under wet H2 (3% H2O) at 800 °C with the introduction of GDC. Under wet CH4 at 900 °C, a maximum power density of 160 mW cm−2 was obtained and no carbon deposition was observed on the anode. It was found that the addition of H2O in the anode caused an increase of electrode ohmic resistance and a decrease of open circuit voltage. Redox cycling stability was investigated and only a slight drop in cell performance was observed after 5 cycles. These results suggest that GDC infiltrated SrMoO3–YSZ is a promising anode material for solid oxide fuel cells.Highlights► Strontium molybdate as an electronic conductor is incorporated in anode. ► Performance improvement both on wet H2 and CH4 oxidation is obtained by GDC infiltration. ► Ni-free GDC infiltrated SrMoO3–YSZ anode shows no carbon deposition problem.
Co-reporter:Lu Lu Zheng, Xin Wang, Lan Zhang, Jing-Yuan Wang, San Ping Jiang
International Journal of Hydrogen Energy 2012 Volume 37(Issue 13) pp:10299-10310
Publication Date(Web):July 2012
DOI:10.1016/j.ijhydene.2012.03.105
Sulfur tolerance of Ni/Gd2O3–CeO2 (Ni/GDC) anodes promoted by impregnated palladium nanoparticles is investigated using the electrochemical impedance spectroscopy (EIS) and galvanostatic polarization techniques in the H2–H2S fuels at 800 °C. The anodes are alternately polarized in pure H2 and H2S-containing H2 fuels with H2S concentration gradually increased from 5 to 700 ppm at 200 mA cm−2. The degradation in performance for the hydrogen oxidation in H2S-containing H2 fuels especially at low H2S concentration is substantially smaller on Pd-impregnated Ni/GDC cermet anodes, as compared to that on pure Ni/GDC anodes. The potential of Pd-impregnated Ni/GDC electrodes measured in pure H2 decreases by 0.07 V after exposure to H2S-containing H2 fuels, substantially smaller than 0.13 V observed on pure Ni/GDC anodes under identical test conditions. The results show that Pd impregnation significantly enhances the sulfur tolerance of Ni/GDC cermet anodes particularly in the low H2S concentration range (e.g., <100 ppm). The results indicate that the enhanced sulfur tolerance of Pd impregnated Ni/GDC anodes is most likely due to the promotion effect of impregnated Pd nanoparticles on the hydrogen dissociation and diffusion processes. The reduced moderation of the morphology and microstructure of the anodes in the presence of Pd nanoparticles may be the result of weaker interaction or adsorption of sulfur on Ni and GDC phases.Highlights► Synthesis and characterization of Pd-impregnated Ni/GDC anodes. ► Pd impregnation enhances sulfur tolerance of Ni/GDC anodes. ► Pd promotes the hydrogen diffusion processes and inhibits the sulfur absorption. ► Pd reduces the sulfur poisoning effect on the microstructure of Ni and GDC phases.
Co-reporter:Son Truong Nguyen, Jong-Min Lee, Yanhui Yang, and Xin Wang
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 30) pp:9966-9972
Publication Date(Web):February 1, 2012
DOI:10.1021/ie202696z
In this study, substoichiometric titanium oxide, TinO2n–1, was compared with carbon black and TiO2 in the role of catalyst supports for Pd in alkaline direct ethanol fuel cell. 10%Pd/C, 10% Pd/commercial TiO2 and 10%Pd/TinO2n–1 catalysts were successfully prepared by a polyol method. The supports and electrocatalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA) techniques. Excellent durability was found for TinO2n–1 with holding potential and multiscan tests in N2-purged 1 M KOH solution. Among the three catalysts, Pd/TinO2n–1 showed the best activity and stability for ethanol electrooxidation in alkaline media.
Co-reporter:Dr. Bao Yu Xia;Wan Theng Ng;Hao Bin Wu; Xin Wang; Xiong Wen (David) Lou
Angewandte Chemie International Edition 2012 Volume 51( Issue 29) pp:7213-7216
Publication Date(Web):
DOI:10.1002/anie.201201553
Co-reporter:Dr. Bao Yu Xia;Wan Theng Ng;Hao Bin Wu; Xin Wang; Xiong Wen (David) Lou
Angewandte Chemie 2012 Volume 124( Issue 29) pp:7325-7328
Publication Date(Web):
DOI:10.1002/ange.201201553
Co-reporter:Yaolun Yu ; Kok Hwa Lim ; Jing Yuan Wang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 5) pp:3851-3856
Publication Date(Web):December 28, 2011
DOI:10.1021/jp210851b
CO stripping experiments were carried out on a series of submonolayer decorated Pt@Au/C electrocatalysts with different Pt surface coverages which were synthesized by the Cu underpotential deposition (UPD)-Pt redox replacement technique. Combined with density functional theory calculations, the correlation between the CO adsorption strength and surface morphology of the catalyst is well illustrated. Results showed that whether the surface Pt atom could form a PtPt surface ensemble with another neighboring Pt atom is critical, which determines CO adsorption and oxidation behaviors on the electrocatalyst.
Co-reporter:Mingzhu Liu, Cheng Wang and Xin Wang
Journal of Materials Chemistry A 2011 vol. 21(Issue 39) pp:15197-15200
Publication Date(Web):01 Sep 2011
DOI:10.1039/C1JM11862E
A novel interface-facilitated synthesis of metal-free graphitic carbon plates with controllable thickness is reported. In contrast to bulk phase synthesis of the conventional hydrothermal method, the process occurs only at the interface due to the enrichment of precursors induced by the organic intermediates, allowing the use of precursors at very low concentration and alleviating the environmental burden.
Co-reporter:Chunmei Zhou, Yuanting Chen, Zhen Guo, Xin Wang and Yanhui Yang
Chemical Communications 2011 vol. 47(Issue 26) pp:7473-7475
Publication Date(Web):31 May 2011
DOI:10.1039/C1CC12264A
The catalytic activity of Pt/CNT for benzyl alcohol aerobic oxidation was remarkably improved by decorating iron oxide on Pt nanoparticles, and electrochemical measurements evidenced the enhanced activation of oxygen and benzyl alcohol at the FeOx/Pt interface.
Co-reporter:Shuangyin Wang, San Ping Jiang, Xin Wang
Electrochimica Acta 2011 Volume 56(Issue 9) pp:3338-3344
Publication Date(Web):30 March 2011
DOI:10.1016/j.electacta.2011.01.016
An effective synthesis strategy of hybrid metal (PtRu)/metal oxide (SnO2) nanoparticles on graphene nanocomposites is developed using a microwave-assisted one-pot reaction process. The mixture of ethylene glycol (EG) and water is used as both solvent and reactant. In the reaction system for the synthesis of SnO2/graphene nanocomposite, EG not only reduces graphene oxide (GO) to graphene, but also results in the formation of SnO2 facilitated by the presence of a small amount of water. On the other hand, in the reaction system for preparation of PtRu/graphene nanocomposites, EG acts as solvent and reducing agent for reduction of PtRu nanoparticles from their precursors and reduction of graphene from graphene oxide. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations confirm the feasibility of the microwave-assisted reaction system to simultaneously reduce graphene oxide and to form SnO2 or PtRu nanoparticles. The as-synthesized SnO2/graphene hybrid composites show a much higher supercapacitance than the pure graphene, and the as-prepared PtRu/graphene show much better electrocatalytic activity for methanol oxidation compared to the commercial E-TEK PtRu/C electrocatalysts.Graphical abstractResearch highlights► Microwave polyol method is efficient to deposit nanoparticles on graphene. ► SnO2/graphene is more efficient than graphene for supercapacitor. ► PtRu/graphene is more active than commercial PtRu/C for methanol oxidation.
Co-reporter:Shuangyin Wang, San Ping Jiang, Xin Wang, Jun Guo
Electrochimica Acta 2011 Volume 56(Issue 3) pp:1563-1569
Publication Date(Web):1 January 2011
DOI:10.1016/j.electacta.2010.10.055
In this work, Pt nanowire networks supported on high surface area carbon (Pt NWNs/C) are synthesized as electrocatalysts for direct methanol fuel cells (DMFCs). The electrocatalytic behavior of Pt NWNs/C catalysts for the methanol and adlayer CO oxidation reactions is investigated and the results are compared with the Pt nanoparticles (NPs) supported on carbon (Pt NPs/C). The results indicate that Pt NWNs are characterized by interconnected nanoparticles with large number of grain boundaries, downshifted d-band center and reduced oxophilicity, which results in the enhanced surface mobility of oxygen-containing species such as COads and OHads. The enhanced surface mobility of COads and OHads in turn facilitates the removal of intermediate CO species during the methanol oxidation. The activity of the Pt NWNs/C electrocatalyst for the methanol oxidation reaction and electrooxidation of adsorbed CO is also evaluated by cyclic voltammetry, CO stripping, and kinetic analysis. The results show that Pt NWNs/C catalysts have a significantly higher electrocatalytic activity for the methanol oxidation reaction as compared to Pt NPs/C catalysts. The enhanced electrocatalytic activity of Pt NWNs/C catalysts is mainly due to the existence of large number of the grain boundaries of the interconnected nanoparticles of the unique Pt NWN structure.
Co-reporter:Shuangyin Wang, Xin Wang and San Ping Jiang
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 15) pp:6883-6891
Publication Date(Web):16 Mar 2011
DOI:10.1039/C0CP02495C
Pt and Au nanoparticles with controlled Pt:Au molar ratios and PtAu nanoparticle loadings were successfully self-assembled onto poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-G) as highly effective electrocatalysts for formic acid oxidation in direct formic acid fuel cells (DFAFCs). The simultaneously assembled Pt and Au nanoparticles on PDDA-G showed superb electrocatalytic activity for HCOOH oxidation, and the current density associated with the preferred dehydrogenation pathway for the direct formation of CO2 through HCOOH oxidation on a Pt1Au8/PDDA-G (i.e., a Pt:Au ratio of 1:8) is 32 times higher than on monometallic Pt/PDDA-G. The main function of the Au in the mixed Pt and Au nanoparticles on PDDA-G is to facilitate the first electron transfer from HCOOH to HCOOads and the effective spillover of HCOOads from Au to Pt nanoparticles, where HCOOads is further oxidized to CO2. The Pt:Au molar ratio and PtAu nanoparticle loading on PDDA-G supports are the two critical factors to achieve excellent electrocatalytic activity of PtAu/PDDA-G catalysts for the HCOOH oxidation reactions.
Co-reporter:Son Truong Nguyen, Delphine Si Ling Tan, Jong-Min Lee, Siew Hwa Chan, Jing Yuan Wang, Xin Wang
International Journal of Hydrogen Energy 2011 Volume 36(Issue 16) pp:9645-9652
Publication Date(Web):August 2011
DOI:10.1016/j.ijhydene.2011.05.049
Various Pd–Tb/C electrocatalysts with different Pd/Tb ratios were synthesized and tested for ethanol oxidation in alkaline media. The structure and morphology of the nanocatalysts were investigated using X-ray diffraction and transmission electron microscopy. The data showed that face-centered cubic structures were formed for all the Pd–Tb/C catalysts and a well dispersion of nanoparticles on carbon black was observed. The electrocatalytic properties of the catalysts for ethanol oxidation in alkaline solution were tested by cyclic voltammetry, linear sweep voltammetry and chronoamperometry techniques. It was found that Pd–Tb/C catalysts have higher activity and durability for ethanol oxidation than Pd/C. This may be attributed to the promotion effect of Tb on OH− adsorption. The highest performance was observed for 10%Pd–2%Tb/C in terms of the highest activity, stability and lowest activation energy for ethanol oxidation.Highlights► Tb as promoter for Pd/C toward the electrooxidation of ethanol in alkaline media. ► Pd–Tb/C catalysts have higher activity for ethanol oxidation than Pd/C. ► The effect of Tb content is examined.
Co-reporter:Yaolun Yu;Kok Hwa Lim
Catalysis Letters 2011 Volume 141( Issue 12) pp:1872-1882
Publication Date(Web):2011/12/01
DOI:10.1007/s10562-011-0719-7
In this work we have systematically characterized the adsorption of formic acid, its decomposed intermediates and products on the (100) surfaces of Pt, Au, monolayer and decorated Pt@Au surfaces. The calculated thermodynamic results validate our previous experimental results that the decorated Pt@Au surface may facilitate formic acid oxidation compared with the benchmark Pt catalyst; while the monolayer Pt@Au surface is not suitable for formic acid oxidation.
Co-reporter:Yi Wang, An Li, Kean Wang, Cong Guan, Weiqiao Deng, Changming Li and Xin Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 31) pp:6490-6494
Publication Date(Web):30 Jun 2010
DOI:10.1039/C0JM00609B
The doping of dispersed lithium (Li) onto multi-wall carbon nanotubes (CNTs) was performed by a solution method for hydrogen storage. The sample with a Li content of 1.2 wt% shows a maximal reversible hydrogen storage capacity of 3.9 wt% at 77 K and 106.66 kPa, which exceeds that of the un-doped CNTs by three times. According to the analyses of X-ray photoelectron spectroscopy, adsorption heat and nitrogen adsorption isotherms, the strong interaction between hydrogen molecules and the Li-doped CNTs, as well as the better charge isolation state of Li, may contribute to the improved hydrogen storage capacity. However, excessive Li may result in a lowering of the charge isolation state and a decrease in specific surface area and pore volume, and thus deteriorate the hydrogen storage capacity.
Co-reporter:Yi Wang, Truong Son Nguyen, Xuewei Liu, Xin Wang
Journal of Power Sources 2010 Volume 195(Issue 9) pp:2619-2622
Publication Date(Web):1 May 2010
DOI:10.1016/j.jpowsour.2009.11.072
Carbon-supported bimetallic palladium–lead (Pd–Pb/C) catalysts with different amounts of lead are prepared using a co-reduction method. The catalysts are characterized by various techniques, which reveal the formation of an alloy nanoparticle structure. The electrochemical activities of the catalysts towards ethanol oxidation in alkaline media are examined by cyclic voltammetry, linear sweep voltammetry and chronoamperometry methods. The results show that the Pd–Pb(4:1)/C catalyst exhibits a better catalytic activity than the Pd/C catalyst. From carbon monoxide (CO) stripping results, the addition of lead also facilitates the oxidative removal of adsorbed CO. The promoting effect of lead is explained by a bi-functional mechanism and d-band theory.
Co-reporter:Tienhoa Nguyen, Xin Wang
Journal of Power Sources 2010 Volume 195(Issue 4) pp:1024-1030
Publication Date(Web):15 February 2010
DOI:10.1016/j.jpowsour.2009.08.049
A highly porous polyimide film with tunable pore size, porosity and thickness is synthesized and used as a matrix to construct a Nafion-infiltrated composite membrane. A very efficient way for an easy and complete infiltration of the proton-conducting polymer into this substrate is developed, which is usually a major problem for composite membranes. Due to the complete inertness to methanol and the very high mechanical strength of the polyimide matrix, the swelling of the composite membrane is greatly suppressed and the methanol crossover is also significantly reduced (80 times), where as while high proton conductivity (comparable with Nafion) and mechanical strength (4 times stronger than Nafion) is still maintained. This membrane demonstrates significantly improved cell performance compared with the Nafion membrane and is a promising candidate for use in direct methanol fuel cells.
Co-reporter:Noel Kristian, Yaolun Yu, Jong-Min Lee, Xuewei Liu, Xin Wang
Electrochimica Acta 2010 Volume 56(Issue 2) pp:1000-1007
Publication Date(Web):30 December 2010
DOI:10.1016/j.electacta.2010.09.073
Carbon-supported PtCo nanoparticles catalysts with core–shell structure were prepared via reduction method and subsequent electroless deposition. It was found that pH has critical effect on the morphology and activity of the synthesized catalyst. The favorable pH to prevent the formation of oxide impurities and extensive Co dissolution during the replacement reaction is neutral. The intrinsic activity of the PtCo/C catalysts for oxygen reduction reaction was found to be 2–4 times higher compared with that of Pt/C. This activity enhancement may originate from the favorable Pt–Pt interatomic distance and low defect that would inhibit the formation of Pt–OHad at low overpotential.
Co-reporter:Shuangyin Wang, San Ping Jiang, T.J. White, Xin Wang
Electrochimica Acta 2010 Volume 55(Issue 26) pp:7652-7658
Publication Date(Web):1 November 2010
DOI:10.1016/j.electacta.2009.09.003
Pt and Pd nanosheaths are successfully synthesized on multi-walled carbon nanotubes (MWCNTs) using the non-covalent poly(diallyldimethylammonium chloride) (PDDA) functionalization and seed-mediated growth methods. In this method, negatively charged Pt or Pd metal precursors are self-assembled with positively charged PDDA-functionalized MWCNTs, forming uniformly distributed Pt or Pd nanoseeds on MWCNTs supports. The contiguous and highly porous Pt and Pd nanosheath structured catalysts are then formed by the seed-mediated growth in corresponding metal precursors using ascorbic acid as the reducing agent. The essential role of uniformly dispersed Pt and Pd nanoseeds on PDDA-MWCNTs is demonstrated. The results indicate that both Pt and Pd nanosheaths show an enhanced catalytic activity for the methanol and formic acid oxidation reaction in acid solution, respectively, as compared with conventional Pt/C and Pd/C catalysts. The enhanced activities are most likely due to the reduced oxophilicity, which results in a weakened chemisorption energy with oxygen-containing species such as COad, and the increased reactive sites due to the large number of grain boundaries of the Pt and Pd nanosheath structured electrocatalysts.
Co-reporter:Shuangyin Wang, Fan Yang, San Ping Jiang, Shengli Chen, Xin Wang
Electrochemistry Communications 2010 Volume 12(Issue 11) pp:1646-1649
Publication Date(Web):November 2010
DOI:10.1016/j.elecom.2010.09.017
Polyelectrolytes with various characteristic functional groups as interlinkers to anchor Pt nanoparticles were used to functionalize carbon nanotubes (CNTs) as Pt electrocatalyst support. It was found that polyanions (poly(styrenesulfonic acid) (PSS), and poly(acrylic acid sodium) (PAA)) have a beneficial effect on methanol electrooxidation on Pt nanoparticles supported on carbon nanotubes via modifying their electronic structure through charge transfer from polyanions to Pt sites and supply of oxygen-containing species. The increased electron density around Pt sites by the charge transfer from polyanions would cause partial filling of Pt 5d-bands, resulting in the downshift of d-band center and weaker chemisorption with oxygen-containing species (e.g. COad). The weakened chemisorption of CO on Pt nanoparticles would promote the methanol electrooxidation. On the contrary, polycations would have an opposite effect on the electronic structure and chemisorption properties of Pt nanoparticles.
Co-reporter:Yi Wang, Jong Min Lee, Xin Wang
International Journal of Hydrogen Energy 2010 Volume 35(Issue 4) pp:1669-1673
Publication Date(Web):February 2010
DOI:10.1016/j.ijhydene.2009.12.026
The Co–Si composites with a molar ratio of 2:1 are synthesized by ball-milling method and their potential as negative electrode materials of Ni–MH batteries is investigated. The microstructure, morphology and chemical state of the ball-milled Co–Si composites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD patterns show that the ball-milled samples for 10 and 20 h contain Co, Si and Co2Si phases, and the ball-milled samples for 40 and 60 h are mainly amorphous Co2Si alloys. In contrast to the high initial discharge capacity (1012 mAh/g) obtained for the sample ball-milled for 10 h, the discharge capacities of the samples ball-milled for 40 and 60 h are very low. It indicates that the hydrogen storage capacity of pure Co2Si alloy is very low. It is found that the formation of active Co nanoparticles and Si oxidation are responsible for the high values of the initial discharge capacities of the ball-milled samples for 10 and 20 h. However, after the first cycle, the discharge capacities of the composites drop below 300 mAh/g. Based on XRD and cyclic voltammetric results, the remaining discharge capacity is mainly contributed by the conversion reaction of Co/Co(OH)2.
Co-reporter:Tien Hoa Nguyen, Cheng Wang, Xin Wang
Journal of Membrane Science 2009 Volume 342(1–2) pp:208-214
Publication Date(Web):15 October 2009
DOI:10.1016/j.memsci.2009.06.042
We have synthesized a porous co-polyimide film by coagulating a polyimide precursor in the non-solvent and thermal imidization. Factors affecting the morphology, pore size, porosity, and mechanical strength of the film were discussed. The porous polyimide matrix consists of a porous top layer and a spongy sub-structure with micropores. It is used as a porous matrix to construct sulfonated poly(styrene-ran-ethylene) (SPSE) infiltrated composite membrane for direct methanol fuel cell (DMFC) application. Due to the complete inertness to methanol and the very high mechanical strength of the polyimide matrix, the swelling of the composite membrane is greatly suppressed and the methanol crossover is also significantly reduced, while high proton conductivity is still maintained. Because of its higher proton conductivity and less methanol permeability, single fuel cell performance test demonstrated that this composite membrane outperformed Nafion membrane. Based on these results, SPSE/polyimide composite membrane has great potential to be used in DMFCs.
Co-reporter:Noel Kristian, Yaolun Yu, Poernomo Gunawan, Rong Xu, Weiqiao Deng, Xuewei Liu, Xin Wang
Electrochimica Acta 2009 Volume 54(Issue 21) pp:4916-4924
Publication Date(Web):30 August 2009
DOI:10.1016/j.electacta.2009.04.018
Highly active Pt-decorated Au nanoparticles on carbon support with Pt:Au mole ratio ranging from 1:10 to 1:2 was successfully synthesized based on successive reduction strategy. The successful formation of this structure was suggested by transmission electron microscopy, UV–vis and voltammetry analyses. The electrocatalytic activity of this decorated structure toward formic acid oxidation surprisingly increases despite the low amount of Pt being used. At 0.1 V, the specific activity of PtAu/C with Pt/Au mole ratio 1:8 was more than one order of magnitude higher than the conventional Pt/C. The enhancement was attributed to the less Pt ensemble sites that the decorated structure possesses (ensemble effect) and the increase in the Pt atom reactivity on Au nanocrystal. The formic acid oxidation mechanism on this decorated structure was also elucidated using electrochemical impedance spectroscopy technique. It is proposed that besides the dehydrogenation reaction pathway happening on clean Pt sites, the reactive intermediate i.e. formate species could also be oxidized by the adsorbed water species on Pt at higher potential.
Co-reporter:Dingsheng Yuan, Jianghua Zeng, Noel Kristian, Yi Wang, Xin Wang
Electrochemistry Communications 2009 Volume 11(Issue 2) pp:313-317
Publication Date(Web):February 2009
DOI:10.1016/j.elecom.2008.11.041
A simple route has been employed to prepare nanosized Bi2O3 deposited on highly ordered mesoporous carbon. The electrochemical measurements reveal that, by loading only 10% Bi2O3 on the mesoporous carbon, the specific capacitance of the composite is improved by 62%, with the maximum value reaching 232 F g−1 at a sweep rate of 5 mV s−1. The specific capacitance of Bi2O3 is calculated and reaches 1305 F g−1 at 1 mV s−1. It is found that the mass transfer in the framework of the crystalline oxide is still difficult in spite of its nanosize, as evidenced by the decline of the specific capacitance of the Bi2O3 with the increase of the sweep rate. The cyclic life of composite materials is also measured and the capacitance only declines 21% after 1000 cycles.
Co-reporter:Yaolun Yu, Yueping Hu, Xuewei Liu, Weiqiao Deng, Xin Wang
Electrochimica Acta 2009 Volume 54(Issue 11) pp:3092-3097
Publication Date(Web):15 April 2009
DOI:10.1016/j.electacta.2008.12.004
Electrochemical study of the decorated Pt@Au catalyst synthesized by Cu underpotential deposition (UPD)-Pt redox replacement technique has been conducted in this work. The parameters affecting the Cu UPD on Au/C nanoparticles in sulfuric acid electrolyte, including the UPD potential, deposition time and potential sweep rate, were investigated in detail. Anode stripping method was used to calculate the charge of the deposited Cu adlayers. Results showed that Pt@Au catalyst prepared by this UPD-redox replacement approach is not a core-shell structure but a decorated structure. A series of decorated Pt@Au/C catalysts with various Pt coverages were synthesized and examined for formic acid oxidation (FAO). It is found that the specific activity of Pt atoms increases with the decrease of Pt surface coverage on Au. Life test showed that better stability was pertained for this decorated Pt@Au/C catalyst compared to Pt/C towards FAO.
Co-reporter:Yi Wang, Truong Son Nguyen, Cheng Wang and Xin Wang
Dalton Transactions 2009 (Issue 37) pp:7606-7609
Publication Date(Web):27 Jul 2009
DOI:10.1039/B909324A
The Pt/C electrocatalysts containing Pr6O11 nanorods were successfully prepared. By various electrochemical characterization methods, it was demonstrated that the Pr6O11 nanorods have an obviously promotive role for ethanol electrooxidation catalyzed by Pt/C. However, according to the stripping experiment, the promotive effect of Pr6O11 does not result from the easier electrooxidation of the intermediate adsorbate on Pt–Pr6O11/C than on Pt/C. It was supposed that Pr6O11 could promote a certain step in ethanol oxidation, and that the special morphology of the nanorods could further enhance the activity compared with nanoparticles.
Co-reporter:Yi Wang, Weiqiao Deng, Xuewei Liu, Xin Wang
International Journal of Hydrogen Energy 2009 Volume 34(Issue 3) pp:1437-1443
Publication Date(Web):February 2009
DOI:10.1016/j.ijhydene.2008.11.085
The structure changes of multi-wall carbon nanotubes (MWNTs) processed by mechanical ball milling and the influence on their electrochemical hydrogen storage capacities were studied. TEM micrographs show that MWNTs are shortened and open-ended after ball milling. The effects of different MWNT type and ball milling time on the discharging capacity were investigated. Among all the samples examined, the sample of short MWNTs with diameter of 5 nm and ball milling time of 12 h has the largest discharge capacity (741.1 mAh/g). According to the analysis of Raman spectra and nitrogen adsorption experiments, it can be inferred that the micropore volume, specific surface area and appropriate defects are crucial to the storage capacity. In the cyclic voltammograms, the hydrogen desorption peak appears prior to hydrogen oxidation peak, which is attributed to the slow reaction of hydrogen oxidation at MWNTs. The results also suggest the possible existence of the strong chemisorption of hydrogen.
Co-reporter:Yi Wang, Weiqiao Deng, Xuewei Liu, Shuangyin Wang, Xin Wang
International Journal of Hydrogen Energy 2009 Volume 34(Issue 3) pp:1444-1449
Publication Date(Web):February 2009
DOI:10.1016/j.ijhydene.2008.11.080
Nanocrystalline LaMg12–Ni composites containing carbon nanotubes (CNTs) were prepared by two ball-milling ways, and the resulting microstructure and electrochemical characteristics were investigated. It is found that the discharge capacities and high-rate dischargeabilities (HRDs) of the CNT-containing composites prepared by ball-milling as-prepared nanocrystalline LaMg12–Ni composite and CNTs for 1 h (denoted as Composite-CNT1-1) were obviously higher than that by ball-milling LaMg12 alloy, Ni powder and CNT1 together for 12 h (denoted as Composite-CNT1-2). The highest discharge capacity reaches 999.8 mA h/g. Raman spectra and X-ray diffraction (XRD) patterns show that the structure of the CNTs still exists and the defect increases in Composite-CNT1-1. However, in Composite-CNT1-2, due to the overlong ball-milling time, the crystalline structure of the CNTs has been destroyed and amorphous carbons have formed. Cyclic voltammetry and electrochemical impedance spectra measurements indicate that the CNT modification in Composite-CNT1-1 increases the electrocatalytic activity and surface area, which leads to its higher discharge capacity and HRD. The larger electrochemical reaction resistance caused by amorphous carbon in Composite-CNT1-2 results in its lower discharge capacity and HRD. The CNT modification has negligible effect on the diffusion process of hydrogen from the surface to the bulk of the composites.
Co-reporter:Tien Hoa Nguyen, Xin Wang
Separation and Purification Technology 2009 Volume 67(Issue 2) pp:208-212
Publication Date(Web):2 June 2009
DOI:10.1016/j.seppur.2009.03.014
We successfully synthesized porous co-polyimide membranes from a polycondensation reaction of an aromatic dianhydride of 3,3′,4,4′-biphenyltetracarboxylicdianhydride (SBPDA) with diamines of p-phenylenediamine (PPDA) and 4,4′-oxydianiline (ODA) by a wet phase inversion process. Factors affecting the mechanical strength of the membrane and porosity were discussed. By tuning the parameters, a spongy type porous membrane with high mechanical strength and high porosity was obtained. In addition, the porous co-polyimide membrane consisted of a porous top layer and a spongy type sub-structure. This material is suitable as the matrix of a multifunctional composite membrane of a direct methanol fuel cell (DMFC) by filling protonic electrolytes in the micropores of the matrix.
Co-reporter:Yonghao Liu, Tienhoa Nguyen, Noel Kristian, Yaolun Yu, Xin Wang
Journal of Membrane Science 2009 330(1–2) pp: 357-362
Publication Date(Web):
DOI:10.1016/j.memsci.2009.01.011
Co-reporter:Li Gao;Xin Ge;Zhanli Chai;Guohai Xu;Cheng Wang
Nano Research 2009 Volume 2( Issue 7) pp:565-574
Publication Date(Web):2009 July
DOI:10.1007/s12274-009-9056-1
Submicrometer sized pure cubic phase, Eu3+ doped, and Yb3+/Er3+ co-doped α-NaYF4 particles with octahedral morphology have been prepared in acetic acid. The acetate anion plays a critical role in the formation of such symmetric octahedral structures through its selective adsorption on the (111) faces of the products. The size of the as-prepared octahedra can be tuned by varying the amount of sodium acetate added to the acetic acid. A possible formation mechanism for these octahedra has been proposed. The doped α-NaYF4 octahedral submicrometer particles show down-conversion and up-conversion photoluminescence typical of these materials.
Co-reporter:Shuangyin Wang, San Ping Jiang, T. J. White, Jun Guo and Xin Wang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 43) pp:18935-18945
Publication Date(Web):October 5, 2009
DOI:10.1021/jp906923z
Platinum nanoparticles (NPs) have been successfully assembled on noncovalently poly(diallyldimethylammonium chloride)-functionalized multiwalled carbon nanotubes (MWCNTs) via microwave-assisted polyol reduction and seed-mediated growth methods. Pt NPs were uniformly deposited on MWCNT support with Pt loading of 10−93 wt %. The results show that the increase in the Pt NP loading on MWCNTs leads to a positive shift of the peak potential for the reduction of Pt−OHad, a negative shift of the peak potential for oxidation of adsorbed CO, an increase in the peak current for the methanol oxidation reaction, and a positive shift for the half-wave potential of the oxygen reduction reaction in acid solutions, even though the size of the Pt NPs also increased with the Pt loading. The increase of the electrocatalytic activity of Pt/MWCNTs shows a characteristic S-shaped profile as a function of the Pt NP loading. To explain the S-shaped dependence of the activity of Pt/MWCNTs on Pt loading, a new concept of interconnectivity of Pt NPs was introduced. Interconnectivity is defined as the ratio of the total number of interconnections between particles divided by the total number of particles involved. The results indicate a close correlation between the electrocatalytic activities of Pt/MWCNTs catalysts and the interconnectivity of Pt NPs on MWCNTs. The electrocatalytic activity of the Pt/MWCNTs was found to first increase linearly and then level off with the interconnectivity of Pt NPs on MWCNTs. The optimum interconnectivity of Pt NPs on MWCNTs is ∼3, which corresponds to a Pt loading of 50 wt % in the Pt/MWCNTs. The reason for the enhanced catalysis with increased interconnectivity of Pt NPs is considered to be associated with a significant increase in the number of grain boundaries, which are considered to contain the active sites for the fuel cell reactions.
Co-reporter:Noel Kristian, Yushan Yan and Xin Wang
Chemical Communications 2008 (Issue 3) pp:353-355
Publication Date(Web):31 Oct 2007
DOI:10.1039/B714230G
A novel structure of catalyst, submonolayer Pt-decorated Au, has been synthesized with minimal use of Pt and shows markedly improved activity toward formic acid oxidation where it facilitates the direct oxidation of formic acid by suppressing the formation of poisonous species COadsvia the “ensemble” effect.
Co-reporter:Xuanying Deng, Xin Wang, Zi-Feng Ma
Journal of Power Sources 2008 Volume 183(Issue 2) pp:604-608
Publication Date(Web):1 September 2008
DOI:10.1016/j.jpowsour.2008.03.092
Composite electrocatalysts based on the transition metal cobalt are synthesized for the oxygen reduction reaction (ORR) by mechanically mixing three basic precursors containing carbon black, cobalt acetate and tetramethoxy-phenylporphyrin (TMPP). The influence of various mixing processes, solvents, pyrolysis temperature and precursor ratios on the ORR activity of the electrocatalysts is investigated by means of their electrochemical characteristics. Levich–Koutecky plots show that the number of transferred electrons during ORR on these catalysts varies between 2 and 4. A pyrolyzed mixture synthesized by ultrasonication exhibits better activity for ORR than that prepared by ball milling. The solvent is found to have a significant effect on the performance of the catalysts in acidic media. The catalyst synthesized in water, a poor solvent of TMPP, has better activity than that synthesized in a good solvent of TMPP, such as N,N-dimethylformamide and acetic acid. The optimum pyrolysis temperature is 600 °C. Various mole ratios and Co/carbon weight ratios are examined. Maximum activity is found at a 1:1 TMPP/Co mole ratio and a 5% Co/carbon weight ratio.
Co-reporter:Dingsheng Yuan, Shaozao Tan, Yingliang Liu, Jianghua Zeng, Fengping Hu, Xin Wang, Peikang Shen
Carbon 2008 Volume 46(Issue 3) pp:531-536
Publication Date(Web):March 2008
DOI:10.1016/j.carbon.2008.01.004
A simple solvothermal method has been used to synthesize highly graphitized lace-like carbon (GLC) using ethanol as the carbon source and Mg as reducing agent. The GLC is characterized by transmission electron microscopy, X-ray diffraction, N2 adsorption, Raman spectroscopy and electrochemical techniques. The GLC synthesized at optimized conditions shows interlaced structure with an average thickness of 3 nm. Platinum on GLC electrocatalysts were prepared for methanol oxidation in acidic media for the first time. They show extremely higher activity for methanol oxidation compared to Pt/C electrocatalyst for the same Pt loadings. GLCs act as structural units to form mesopores and channels in the catalyst layers, which lead to the increase of the electrochemical active surface area and improvement in the mass transport by reducing the liquid sealing effect.
Co-reporter:Shuangyin Wang, Noel Kristian, Sanping Jiang, Xin Wang
Electrochemistry Communications 2008 Volume 10(Issue 7) pp:961-964
Publication Date(Web):July 2008
DOI:10.1016/j.elecom.2008.04.018
Platinum submonolayer decorated gold nanorods with controlled coverage were prepared by the addition of Au nanorods into the growth solution of Pt in the presence of NH2OH · HCl as the growth agent. The properties of Au nanorods decorated by Pt submonolayer were investigated by various techniques including transimission electron microscopy, X-ray diffraction, and electrochemical methods. The Pt decorated Au nanorods on carbon black showed significantly higher activity on formic acid electrooxidation than the conventional Pt/C catalysts. They showed different reaction path of formic acid electrooxidation by suppressing the formation of poisoning intermediate CO.
Co-reporter:Yongliang Li, Feng Ping Hu, Xin Wang, Pei Kang Shen
Electrochemistry Communications 2008 Volume 10(Issue 7) pp:1101-1104
Publication Date(Web):July 2008
DOI:10.1016/j.elecom.2008.05.025
We attempted the treatment of multiwalled carbon nanotubes (MWCNTs) in hydrofluoric acid (HF) aqueous solution for depositing Pt nanoparticles as catalysts for methanol oxidation for the first time. The preliminary results revealed that the Pt nanoparticles could be well dispersed on HF treated MWCNTs and gave enhanced activity and stability for methanol oxidation. As demonstrated in this study, the Pt supported on HF treated MWCNTs catalyst gave over doubled current density than that of Pt supported on as-received MWCNTs for methanol oxidation at the same Pt loadings. The enhancement in the stability of the Pt supported on HF treated MWCNTs catalyst for methanol oxidation is believed due to the stronger interaction between Pt nanoparticles and MWCNTs. This study opens promising possibilities for anchoring metal nanoparticles on the walls of the MWCNTs uniformly and stably.
Co-reporter:Yi Wang and Xin Wang
Dalton Transactions 2008 (Issue 40) pp:5495-5500
Publication Date(Web):07 May 2008
DOI:10.1039/B801213J
The Ce5Mg41 hydrogen storage alloy was ball-milled with Ni powder, leading to the formation of a structure of inlaid metallic Ni nanocrystallites dispersed throughout a Ce–Mg amorphous alloy matrix. This structure was identified to have a positive effect on improving electrochemical hydrogen storage capacity. The ball-milled Ce5Mg41 + 200 wt% Ni composite shows the highest initial discharge capacity (1046 mA h g−1) and high-rate dischargeability (HRD). Electrochemical impedance spectra, cyclic voltammograms and anodic polarization measurements show that the high discharge capacity and HRD was due to high hydrogen diffusivity and low reaction resistance. With a further increase in Ni content, the discharge capacity and HRD decreases, as a result of the excessively high reaction resistance due to the presence of an excessive oxide film of Ni(OH)2. However, the cycling stability improves with the increase of Ni content in the nanocomposite.
Co-reporter:Yi Wang, Shizhang Qiao, Xin Wang
International Journal of Hydrogen Energy 2008 Volume 33(Issue 19) pp:5066-5072
Publication Date(Web):October 2008
DOI:10.1016/j.ijhydene.2008.06.038
The electrochemical hydrogen storage properties of the ball-milled PrMg12−xNix + 150 wt% Ni (x = 1 and 2) composites were investigated, and compared with those of the ball-milled PrMg12 + 150 wt% Ni composite. The ball-milled PrMg11Ni–Ni composite has the highest initial discharge capacity (973 mAh/g) and high-rate dischargeability (HRD). The cycle life improves with the increase of Ni content, which was confirmed by the XRD results of the ball-milled composites after 10 cycles. By means of electrochemical impedance spectra, linear polarization and anodic polarization measurements, the electrochemical kinetic parameters were studied. It is suggested that the high hydrogen diffusivity and moderate reaction resistance are responsible for the higher discharge capacity and HRD of the PrMg11Ni–Ni sample, while the lower discharge capacity and HRD of the PrMg10Ni2–Ni sample is probably due to the excessively high reaction resistance.
Co-reporter:Yi Wang, Shizhang Qiao, Xin Wang
International Journal of Hydrogen Energy 2008 Volume 33(Issue 3) pp:1023-1027
Publication Date(Web):February 2008
DOI:10.1016/j.ijhydene.2007.11.020
The electrochemical characteristics of the ball-milled NdMg12NdMg12 alloys with Ni powders were investigated. The first discharge capacity of the ball-milled sample was improved from 770 to 1200 mAh/g when the Ni content in the alloy was increased from 150 to 200 wt%. Furthermore, the first discharge capacity of the ball-milled NdMg12+200wt% Ni composite was very close to that of the ball-milled PrMg12+200wt% Ni composite. However, the high rate dischargeability of the former was not as good as that of the latter. Further analysis by electrochemical impedance spectroscopy (EIS) technique reveals a larger reaction resistance in the ball-milled NdMg12+200wt% Ni composite, probably due to the formation of Nd oxide or Nd(OH)3Nd(OH)3 film on the surface of alloy. Larger reaction resistance resulted in the lower high rate dischargeability of this sample. In addition, the ball-milled NdMg12+200wt% Ni composite exhibited better cycle performance due to the existence of the corrosion resistant Nd oxide or Nd(OH)3Nd(OH)3 film.
Co-reporter:Shuangyin Wang, Xin Wang and San Ping Jiang
Langmuir 2008 Volume 24(Issue 18) pp:10505-10512
Publication Date(Web):August 9, 2008
DOI:10.1021/la800925t
A new synthesis method for the preparation of high-performance PtRu electrocatalysts on multiwalled carbon nanotubes (MWCNTs) is reported. In this method, bimetallic PtRu electrocatalysts are deposited onto 1-aminopyrene (1-AP)-functionalized MWCNTs by a microwave-assisted polyol process. The noncovalent functionalization of MWCNTs by 1-AP is simple and can be carried out at room temperature without the use of expensive chemicals or corrosive acids, thus preserving the integrity and the electronic structure of MWCNTs. PtRu electrocatalysts on 1-AP-functionalized MWCNTs show much better distribution with no formation of aggregates, higher electrochemically active surface area, and higher electrocatalytic activity for the electrooxidation of methanol in direct methanol fuel cells as compared to that on conventional acid-treated MWCNTs and carbon black supported PtRu electrocatalysts. PtRu electrocatalysts on 1-AP-functionalized MWCNTs also show significantly enhanced stability.
Co-reporter:Yi Wang, Xin Wang, Xueping Gao, Panwen Shen
International Journal of Hydrogen Energy 2007 Volume 32(Issue 17) pp:4180-4185
Publication Date(Web):December 2007
DOI:10.1016/j.ijhydene.2007.06.004
The electrochemical hydrogen storage properties of the ball-milled LaMg10-xTixNi2LaMg10-xTixNi2 alloys with Ni powders (x=1x=1 and 2) were investigated. It was found that the first discharge capacity of the ball-milled LaMg9TiNi2+150wt% Ni composite was 909.5 mAh/g, but the value of the ball-milled LaMg8Ti2Ni2+150wt% Ni composite was only 750.2 mAh/g. By EIS analysis, it is shown that the existence of a small quantity of TiNi phase in LaMg9TiNi2LaMg9TiNi2 alloy increased the electro-catalytic activity and reduced the electrochemical reaction resistance. This probably played an important role in the increase of discharge capacity of the ball-milled LaMg9TiNi2–NiLaMg9TiNi2–Ni composite. The presence of LaMg2LaMg2 phase and excessive TiNi phase resulted in the lower discharge capacity of the ball-milled LaMg8Ti2Ni2–NiLaMg8Ti2Ni2–Ni composite. Besides the higher discharge capacity, the ball-milled LaMg9TiNi2–NiLaMg9TiNi2–Ni composite exhibited the better cycle performance. The main reason for the better cycle performance was analyzed by X-ray diffraction (XRD), electrochemical impedance spectra (EIS) and steady-state polarization (SSP) experiments. It is verified that the main reason is that the electrochemical reaction resistance of the ball-milled LaMg9TiNi2–NiLaMg9TiNi2–Ni composite is always lower than that of the ball-milled LaMg10Ni2–NiLaMg10Ni2–Ni composite because the former one contains a small quantity of TiNi phase which has high electro-catalytic activity.
Co-reporter:Son Truong Nguyen, Hiu Mung Law, Hoa Tien Nguyen, Noel Kristian, Shuangyin Wang, Siew Hwa Chan, Xin Wang
Applied Catalysis B: Environmental (7 September 2009) Volume 91(Issues 1–2) pp:507-515
Publication Date(Web):7 September 2009
DOI:10.1016/j.apcatb.2009.06.021
Co-reporter:Yi Wang and Xin Wang
Dalton Transactions 2008(Issue 40) pp:NaN5500-5500
Publication Date(Web):2008/05/07
DOI:10.1039/B801213J
The Ce5Mg41 hydrogen storage alloy was ball-milled with Ni powder, leading to the formation of a structure of inlaid metallic Ni nanocrystallites dispersed throughout a Ce–Mg amorphous alloy matrix. This structure was identified to have a positive effect on improving electrochemical hydrogen storage capacity. The ball-milled Ce5Mg41 + 200 wt% Ni composite shows the highest initial discharge capacity (1046 mA h g−1) and high-rate dischargeability (HRD). Electrochemical impedance spectra, cyclic voltammograms and anodic polarization measurements show that the high discharge capacity and HRD was due to high hydrogen diffusivity and low reaction resistance. With a further increase in Ni content, the discharge capacity and HRD decreases, as a result of the excessively high reaction resistance due to the presence of an excessive oxide film of Ni(OH)2. However, the cycling stability improves with the increase of Ni content in the nanocomposite.
Co-reporter:Yi Wang, Truong Son Nguyen, Cheng Wang and Xin Wang
Dalton Transactions 2009(Issue 37) pp:NaN7609-7609
Publication Date(Web):2009/07/27
DOI:10.1039/B909324A
The Pt/C electrocatalysts containing Pr6O11 nanorods were successfully prepared. By various electrochemical characterization methods, it was demonstrated that the Pr6O11 nanorods have an obviously promotive role for ethanol electrooxidation catalyzed by Pt/C. However, according to the stripping experiment, the promotive effect of Pr6O11 does not result from the easier electrooxidation of the intermediate adsorbate on Pt–Pr6O11/C than on Pt/C. It was supposed that Pr6O11 could promote a certain step in ethanol oxidation, and that the special morphology of the nanorods could further enhance the activity compared with nanoparticles.
Co-reporter:Larissa Thia, Mingshi Xie, Donghwan Kim and Xin Wang
Catalysis Science & Technology (2011-Present) 2017 - vol. 7(Issue 4) pp:NaN881-881
Publication Date(Web):2017/01/24
DOI:10.1039/C6CY02580C
Formic acid and its salts are important chemical intermediates. Industrial production of formic acid involves liquid phase carbonylation of methanol to methyl formate followed by hydrolysis to formic acid. Alternatively, formic acid can be generated during glycerol electro-oxidation when glycerol undergoes C–C bond cleavage. Silver based catalysts such as carbon supported silver–gold alloys significantly improve selectivity to formic acid during glycerol electro-oxidation. However, these catalysts tend to suffer from poor electro-chemical activity. Herein, we examined the ability of Ag containing, porous Au structures to tune the glycerol oxidation pathway towards formate and glycolate whilst maintaining high electro-catalytic activity. Our catalyst consisted of an Au rich porous framework that possessed residual amounts of Ag within its pores. When tested for glycerol electro-oxidation, the Ag containing porous Au catalyst exhibited both high selectivity towards formate and high electrochemical activity.
Co-reporter:Mingzhu Liu, Ya Yan, Lan Zhang, Xin Wang and Cheng Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 23) pp:NaN11461-11461
Publication Date(Web):2012/04/20
DOI:10.1039/C2JM31484C
Deflated-balloon-like and crumpled carbon nanosheets were prepared via a low-temperature hydrothermal carbonization of glucose at the two-phase interfaces. A low amount of glucose and a high amount of sodium dodecyl sulfate were found to be propitious to the formation of graphitic carbon nanosheets with low thickness. Their applications as supercapacitive materials were demonstrated.
Co-reporter:Ya Yan, Bao Yu Xia, Bin Zhao and Xin Wang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 45) pp:NaN17603-17603
Publication Date(Web):2016/10/17
DOI:10.1039/C6TA08075H
Production of hydrogen by water splitting is an appealing solution for sustainable energy storage. Development of bifunctional catalysts that are active for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a key factor in enhancing electrochemical water splitting activity and simplifying the overall system design. Here, recent developments in HER–OER bifunctional catalysts are reviewed. Several main types of bifunctional water splitting catalysts such as cobalt-, nickel- and iron-based materials are discussed in detail. Particular attention is paid to their synthesis, bifunctional catalytic activity and stability, and strategies for activity enhancement. The current challenges faced are also concluded and future perspectives towards bifunctional water splitting electrocatalysts are proposed.
Co-reporter:Zhenchao Lei, Weiming Feng, Chunhua Feng, Weijia Zhou, Chaohai Wei and Xin Wang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 5) pp:NaN2020-2020
Publication Date(Web):2016/12/08
DOI:10.1039/C6TA09887H
The handling of a huge amount of sludge produced from industrial wastewater treatment plants is a critical issue. We report a facile and cost-effective pyrolysis approach to transform coke wastewater sludge flocs into valuable carbon materials that show the potential of being used in energy-storage devices and fuel cells. The nitrified sludge flocs are naturally rich in carbon, nitrogen, sulfur, and other inorganic particles and thus are attractive precursors for producing N,S dual-doped carbon with a hierarchical mesoporous graphene-like structure via the simple one-step pyrolysis method without the addition of external N- and/or S-containing organic compounds, chemical activation agents, or graphitization catalyst precursors. Owing to its unique features, the resulting nitrified sludge floc derived carbon (NSFC) exhibits outstanding capacitive performance. The specific capacitance determined in 1 M H2SO4 at a current density of 1 A g−1 is 889 F g−1, the highest among reported values for carbon-based materials in inorganic electrolytes, as far as we are aware. The NSFC also shows an excellent cycling stability with only 1.2% loss in capacitance after 10000 cycles at a current density of 20 A g−1. The NSFC also achieves superior activity towards the oxygen reduction reaction (ORR) and proves to be a promising metal-free ORR electrocatalyst showing comparable electrocatalytic performance, higher selectivity, and longer durability as compared to the commercial Pt/C benchmark.
Co-reporter:Shuangyin Wang, Xin Wang and San Ping Jiang
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 15) pp:NaN6891-6891
Publication Date(Web):2011/03/16
DOI:10.1039/C0CP02495C
Pt and Au nanoparticles with controlled Pt:Au molar ratios and PtAu nanoparticle loadings were successfully self-assembled onto poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-G) as highly effective electrocatalysts for formic acid oxidation in direct formic acid fuel cells (DFAFCs). The simultaneously assembled Pt and Au nanoparticles on PDDA-G showed superb electrocatalytic activity for HCOOH oxidation, and the current density associated with the preferred dehydrogenation pathway for the direct formation of CO2 through HCOOH oxidation on a Pt1Au8/PDDA-G (i.e., a Pt:Au ratio of 1:8) is 32 times higher than on monometallic Pt/PDDA-G. The main function of the Au in the mixed Pt and Au nanoparticles on PDDA-G is to facilitate the first electron transfer from HCOOH to HCOOads and the effective spillover of HCOOads from Au to Pt nanoparticles, where HCOOads is further oxidized to CO2. The Pt:Au molar ratio and PtAu nanoparticle loading on PDDA-G supports are the two critical factors to achieve excellent electrocatalytic activity of PtAu/PDDA-G catalysts for the HCOOH oxidation reactions.
Co-reporter:Noel Kristian, Yushan Yan and Xin Wang
Chemical Communications 2008(Issue 3) pp:NaN355-355
Publication Date(Web):2007/10/31
DOI:10.1039/B714230G
A novel structure of catalyst, submonolayer Pt-decorated Au, has been synthesized with minimal use of Pt and shows markedly improved activity toward formic acid oxidation where it facilitates the direct oxidation of formic acid by suppressing the formation of poisonous species COadsvia the “ensemble” effect.
Co-reporter:Ya Yan, Baoyu Xia, Xiaoying Qi, Haibo Wang, Rong Xu, Jing-Yuan Wang, Hua Zhang and Xin Wang
Chemical Communications 2013 - vol. 49(Issue 43) pp:NaN4886-4886
Publication Date(Web):2013/03/13
DOI:10.1039/C3CC41031E
A novel electrocatalyst of layered MoS2 supported on reduced graphene oxide (RGO) decorated with nano-sized tungsten carbide (WC) shows an enhanced catalytic performance in the hydrogen evolution reaction, which could be attributed to the presence of a conductive and electrocatalytically-active nano-WC dispersant and the positive synergistic effect between nano-WC/RGO and layered MoS2.
Co-reporter:Ya Yan, BaoYu Xia, Nan Li, Zhichuan Xu, Adrian Fisher and Xin Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 1) pp:NaN135-135
Publication Date(Web):2014/11/07
DOI:10.1039/C4TA04858J
The development of non-noble-metal based hydrogen-evolving catalysts is essential to the practical application of water-splitting devices. Improvement of both the activity and stability of such catalysts remains a key challenge. In this work, a simple solvothermal method is developed to directly grow MoS2 and WS2 on carbon cloth with vertically oriented nanosheet layers. With the unique layer orientation that maximally exposes active edge sites as well as a rapid release of small gas bubbles to maintain a large working area, such prepared 3-dimensional electrodes exhibit high activity towards the HER. In addition, they also exhibit prominent electrochemical durability, thanks to the strong bonding between the nanosheet layers and the substrate along with the self-removal of the as-formed H2 bubbles from the nano-porous electrode surface.
Co-reporter:Yi Wang, An Li, Kean Wang, Cong Guan, Weiqiao Deng, Changming Li and Xin Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 31) pp:NaN6494-6494
Publication Date(Web):2010/06/30
DOI:10.1039/C0JM00609B
The doping of dispersed lithium (Li) onto multi-wall carbon nanotubes (CNTs) was performed by a solution method for hydrogen storage. The sample with a Li content of 1.2 wt% shows a maximal reversible hydrogen storage capacity of 3.9 wt% at 77 K and 106.66 kPa, which exceeds that of the un-doped CNTs by three times. According to the analyses of X-ray photoelectron spectroscopy, adsorption heat and nitrogen adsorption isotherms, the strong interaction between hydrogen molecules and the Li-doped CNTs, as well as the better charge isolation state of Li, may contribute to the improved hydrogen storage capacity. However, excessive Li may result in a lowering of the charge isolation state and a decrease in specific surface area and pore volume, and thus deteriorate the hydrogen storage capacity.
Co-reporter:Yi Wang, Huili Liu, Li Wang, Haibo Wang, Xuan Du, Fang Wang, Tao Qi, Jong-Min Lee and Xin Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 23) pp:NaN6848-6848
Publication Date(Web):2013/04/04
DOI:10.1039/C3TA10214A
A large-area three-dimensional (3D) reduced graphene oxide (TRGO) material was obtained by facile heat treatment of a two-dimensional (2D) reduced graphene oxide (RGO) material. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption results reveal that the new material is composed of small and fluffy graphene nanosheets, with many graphene arrays as well as 3D interconnected macropores and mesopores in some local positions, and possesses an ultrahigh specific surface area (>1000 m2 g−1) and large pore volume. The material was used to support a Pd catalyst for formic acid electrooxidation, demonstrating a much better electrocatalytic activity in terms of the onset potential and peak current density (seven times larger) than that of conventional carbon black, the most popular catalyst support. To tailor the electronic properties, the TRGO material was further functionalized with chitosan (CS). Compared to the Pd loaded on TRGO, Pd nanoparticles supported on the CS-functionalized TRGO show a better catalytic activity and good stability. This work provides a promising catalyst support material for direct formic acid fuel cells.
Co-reporter:Chunmei Zhou, Yuanting Chen, Zhen Guo, Xin Wang and Yanhui Yang
Chemical Communications 2011 - vol. 47(Issue 26) pp:NaN7475-7475
Publication Date(Web):2011/05/31
DOI:10.1039/C1CC12264A
The catalytic activity of Pt/CNT for benzyl alcohol aerobic oxidation was remarkably improved by decorating iron oxide on Pt nanoparticles, and electrochemical measurements evidenced the enhanced activation of oxygen and benzyl alcohol at the FeOx/Pt interface.
Co-reporter:Le Tao, Haibo Wang, Mingshi Xie, Larissa Thia, Wei Ning Chen and Xin Wang
Chemical Communications 2015 - vol. 51(Issue 61) pp:NaN12173-12173
Publication Date(Web):2015/05/22
DOI:10.1039/C5CC03188E
A novel design of a microbial fuel cell is realized by constructing bio-cocatalyst beads immobilized with riboflavin-secreting Escherichia coli and decoupling them from an anodic biocatalyst. A microbial fuel cell loaded with these bio-cocatalyst beads shows significantly enhanced performance without occupying an active electrode surface area.
Co-reporter:Mingzhu Liu, Cheng Wang and Xin Wang
Journal of Materials Chemistry A 2011 - vol. 21(Issue 39) pp:NaN15200-15200
Publication Date(Web):2011/09/01
DOI:10.1039/C1JM11862E
A novel interface-facilitated synthesis of metal-free graphitic carbon plates with controllable thickness is reported. In contrast to bulk phase synthesis of the conventional hydrothermal method, the process occurs only at the interface due to the enrichment of precursors induced by the organic intermediates, allowing the use of precursors at very low concentration and alleviating the environmental burden.
Co-reporter:Bao Yu Xia, Bao Wang, Hao Bin Wu, Zhaolin Liu, Xin Wang and Xiong Wen (David) Lou
Journal of Materials Chemistry A 2012 - vol. 22(Issue 32) pp:
Publication Date(Web):
DOI:10.1039/C2JM32816J
Co-reporter:Thandavarayan Maiyalagan, Xiaochen Dong, Peng Chen and Xin Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 12) pp:NaN5290-5290
Publication Date(Web):2012/02/13
DOI:10.1039/C2JM16541D
A three-dimensional interconnected graphene monolith was used as an electrode support for pulsed electrochemical deposition of platinum (Pt) nanoparticles. Pt nanoparticles with well-defined morphology and small size can be obtained by controlling electrodeposition potential and time. Electrochemical characterization was carried out to examine the electrocatalytic activity of this monolithic electrode towards methanol oxidation in acidic media. The results show that the carbon material surface and structure have a strong influence on the Pt particle size and morphology. Compared with the three-dimensional scaffold of carbon fibers, the three-dimensional graphene when used as a free-standing electrode support resulted in much improved catalytic activity for methanol oxidation in fuel cells due to its three-dimensionally interconnected seamless porous structure, high surface area and high conductivity.
Co-reporter:Ya Yan, Bin Zhao, Sung Chul Yi and Xin Wang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 33) pp:NaN13010-13010
Publication Date(Web):2016/07/28
DOI:10.1039/C6TA05317C
Electrocatalytic water splitting is a promising means for clean energy production. There is a great need to develop low cost, efficient and durable electrocatalysts for such purposes. Herein, we report a novel hierarchical nanostructure composed of FeP porous nanorods on CNT backbones. The directed growth of α-FeO(OH) nanospindles on CNTs was first realized via a bottom-up assembly, followed by phosphorization transformation. When evaluated for the electrocatalytic water splitting reaction, these hierarchical structures exhibited superior oxygen evolution performance due to their advantageous structural features.
Co-reporter:Bao Yu Xia, Hao Bin Wu, Jun Song Chen, Zhiyu Wang, Xin Wang and Xiong Wen (David) Lou
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 2) pp:NaN476-476
Publication Date(Web):2011/11/17
DOI:10.1039/C1CP23367J
TiO2
nanoparticles-decorated graphene nanosheets have been prepared by a facile hydrothermal method. After depositing Pt nanoparticles exclusively around the interface between TiO2 and rGO, the obtained Pt/TiO2@rGO electrocatalyst exhibits remarkably enhanced electrocatalytic performance, which could be attributed to the unique structure and some possible synergetic effect from the 3-phase Pt–TiO2–rGO junctions.
Co-reporter:Nan Li, Larissa Thia and Xin Wang
Chemical Communications 2014 - vol. 50(Issue 30) pp:NaN4006-4006
Publication Date(Web):2014/02/18
DOI:10.1039/C4CC00412D
A specific bifunctional molecule containing amidine is prepared to construct a CO2-responsive surface via molecular self-assembly. The smart surface undergoes CO2-responsive switching of surface charges and wettability, leading to distinctively selective adsorption of hydrophobic/hydrophilic molecules.
Co-reporter:Le Tao, Mingshi Xie, Geraldine Giap Ying Chiew, Zhijuan Wang, Wei Ning Chen and Xin Wang
Chemical Communications 2016 - vol. 52(Issue 37) pp:NaN6295-6295
Publication Date(Web):2016/04/07
DOI:10.1039/C6CC00976J
A novel nondestructive strategy of improving electron trans-inner membrane movements in bioelectrocatalysts is realized by overexpressing NADH dehydrogenase II in the inner membrane. A microbial fuel cell loaded with these improved bioelectrocatalysts shows significantly enhanced performance based on promoting the utilization of intracellular primary electron donors in bioelectrocatalysts.
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