Co-reporter:Cuncai Lv, Zhen Peng, Yaoxing Zhao, Zhipeng Huang and Chi Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 4) pp:1454-1460
Publication Date(Web):22 Dec 2015
DOI:10.1039/C5TA08715E
The development of an effective, non-precious electrocatalyst for the hydrogen evolution reaction (HER) is highly desirable for the commercial application of hydrogen as a clean and renewable energy and remains a substantial challenge. Herein, a hierarchical nanowires array (HNA) of iron phosphide (FeP) nanowires coated with iron phosphide nanorods grown on a carbon fiber paper (CFP) was constructed which exhibited remarkable catalytic activity in the HER. The overpotential required for the current density of 20 mA cm−2 is as small as 45 and 221 mV in acidic and basic solution, respectively, corresponding to Tafel slopes of 53 and 134 mV dec−1. The effective catalytic activity of the CFP–FeP HNA in the HER, together with its long-term stability and nearly 100% faradaic efficiency in water electrolysis, make the CFP–FeP HNA one of the best non-noble electrocatalysts described to date. The prominent catalytic activity of CFP–FeP HNA is correlated to the large number of active sites for the HER, and the fast electron transport from the CFP to the FeP nanorods mediated by FeP nanowires.
Co-reporter:Jinhui Hao;Wenshu Yang;Chi Zhang
Advanced Materials Interfaces 2016 Volume 3( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/admi.201600236
Bifunctional, binder-free, and non-precious-metal electrocatalysts with superwetting properties are of great significance for high-performance oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Herein, the fabrication of copper phosphide (Cu3P) microsheets through the phosphidation of CuCl microsheets deposited onto nickel foam, and the effective catalytic activity of the Cu3P microsheets in the HER and OER is demonstrated. Due to their hierarchical structure, the Cu3P microsheets are superhydrophilic and superaerophobic. A well-defined superhydrophilic surface enhances the electrolyte–electrode contact, and a superaerophobic surface facilitates bubbles extraction and efficiently minimizes the dead area of the electrode induced by bubble coverage. These two features are beneficial for the high activity and stability of the electrocatalysts during the OER and HER. The superhydrophilic and superaerophobic Cu3P microsheets prepared at 450 °C afford a current density of 10 mA cm–2 at an overpotential of 290 mV for the OER and 130 mV for the HER. This work highlights a simple, low-cost approach that can be easily scaled-up to construct high-performance electrocatalysts for the OER and HER.
Co-reporter:HAN XIA;ZHEN PENG;CUNCAI L V;YAOXING ZHAO;JINHUI HAO
Journal of Chemical Sciences 2016 Volume 128( Issue 12) pp:1879-1885
Publication Date(Web):2016 December
DOI:10.1007/s12039-016-1192-z
Development of hybrid electrocatalysts with high activity and good stability is crucial for oxygen evolution reaction (OER) of water electrocatalysis. In this work, cobalt oxide (Co3O4) nanowires loaded on carbon fiber paper (CFP) were synthesized via hydrothermal method and annealing. The as-synthesized Co3O4 nanowires exhibit an enhanced catalytic activity with low onset overpotential (1.52 V vs. RHE) and a small overpotential of 330 mV for a current density of 10 mA cm−2 with a Tafel slope of 60 mV ⋅ dec−1. In addition, the Co3O4 nanowires maintain its electrocatalytic activity for at least 24 h in basic media. The enhanced performance of Co3O4 nanowires/CFP can be attributed to the high conductivity of CFP, the synergistic effect of Co3O4 and carbon, and high porosity of the nanowire. This study will open new possibilities for exploring water electrocatalysis.
Co-reporter:Cuncai Lv, Zhibo Chen, Zhongzhong Chen, Bin Zhang, Yong Qin, Zhipeng Huang and Chi Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 34) pp:17669-17675
Publication Date(Web):24 Jul 2015
DOI:10.1039/C5TA03438H
Iron phosphide (FeP) was introduced onto silicon nanowires (SiNWs) via precursor loading and phosphorization. The resultant SiNWs/FeP shows remarkably enhanced photoelectrochemical hydrogen production in comparison with bare SiNWs. The solar power conversion efficiency of SiNWs/FeP is as high as 2.64%, which is 94% of that of SiNWs modified with Pt particles, and is larger than those of silicon-based photocathodes loaded with other non-precious electrocatalysts such as transition metals and their chalcogenides. The faster reaction rate of the hydrogen evolution reaction (HER) on the surface of the SiNWs/FeP than that of the bare SiNWs was confirmed by an electrochemistry impedance experiment (EIS). The investigations over the EIS spectra and the flat band potential show that the onset potential of cathodic photocurrent is mainly influenced by the reaction rate of the HER on the surface of the photocathode. The transient photocurrent experiments also suggest the faster kinetics of the HER on the surface of the SiNWs/FeP in comparison with that of the bare SiNWs. This result demonstrates a convenient approach to SiNWs loaded with a highly effective electrocatalyst and its promising application potential in photoelectrochemical hydrogen generation.
Co-reporter:Zhipeng Huang, Cuncai Lv, Zhongzhong Chen, Zhibo Chen, Feng Tian, Chi Zhang
Nano Energy 2015 Volume 12() pp:666-674
Publication Date(Web):March 2015
DOI:10.1016/j.nanoen.2015.01.027
•The nanocomposite of diiron phosphide and nitrogen-doped graphene was conveniently synthesized.•The nanocomposite exhibits efficient electrocatalytic activity in hydrogen evolution reaction.•Diiron phosphide is the active component and nitrogen-doped graphene acts as a conductive support.A nanocomposite comprising diiron phosphide (Fe2P) nanoparticles and nitrogen-doped graphene (NGr) was synthesized by a facile one-pot reaction. Such a nanocomposite showed efficient electrocatalytic activity in hydrogen evolution reaction (HER) in both acidic and basic solutions. The optimal overpotential required for the current density of 20 mA cm−2 (η20) in acidic solution is 164 mV, which is favourably comparable to those of recently reported non-precious electrocatalysts; whereas in basic solution the value of η20 is 376 mV. The HER activity of Fe2P/NGr can be correlated to Fe2P nanoparticles in the nanocomposite, and NGr is beneficial to the electron transport from electrode to the catalyst. The faradaic efficiency of Fe2P/NGr nanocomposite in HER is nearly 100% in both acidic and basic solutions. The stability of Fe2P/NGr nanocomposite during HER has been demonstrated by potentiostatic electrolysis and accelerated degradation experiments. Tafel slope was determined to be 65 mV dec−1, which suggests that the HER processes might proceed along a Volmer–Heyrovsky mechanism. The catalytic activity of Fe2P/NGr nanocomposite is influenced by synthesis temperature, which may result in the differences in phase purity, particle size and specific surface areas of the composite material. The charged natures of Fe and P in Fe2P nanoparticle might be responsible for the HER activity of Fe2P/NGr nanocomposite.
Co-reporter:Zhipeng Huang, Maoying Li, Ding Jia, Peng Zhong, Feng Tian, Zhongzhong Chen, Mark G. Humphrey and Chi Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 8) pp:1418-1426
Publication Date(Web):25 Nov 2013
DOI:10.1039/C3TC31919A
Semiconductor–semiconductor hetero-nanorods (Ag2Se–CdSe and Ag2Se–ZnSe) with high crystallinity have been synthesized by a facile and low-cost method. High resolution transmission electron microscopy investigations reveal that the growth follows a catalyst-assisted mechanism. A preliminary investigation of nonlinear optical properties shows that the hetero-nanorods exhibit significantly enhanced third-order nonlinear optical properties. The free carrier absorption cross-section of Ag2Se–CdSe hetero-nanorods is one order of magnitude higher than that of the corresponding single component CdSe nanocrystals. The results obtained in this study represent a new approach to the design and construction of metal selenide hetero-nanorods with high crystallinity and enhanced nonlinear optical capabilities.
Co-reporter:Zhipeng Huang, Zhibo Chen, Zhongzhong Chen, Cuncai Lv, Hua Meng, and Chi Zhang
ACS Nano 2014 Volume 8(Issue 8) pp:8121
Publication Date(Web):July 28, 2014
DOI:10.1021/nn5022204
The exploitation of a low-cost catalyst is desirable for hydrogen generation from electrolysis or photoelectrolysis. In this study we have demonstrated that nickel phosphide (Ni12P5) nanoparticles have efficient and stable catalytic activity for the hydrogen evolution reaction. The catalytic performance of Ni12P5 nanoparticles is favorably comparable to those of recently reported efficient nonprecious catalysts. The optimal overpotential required for 20 mA/cm2 current density is 143 ± 3 mV in acidic solution (H2SO4, 0.5 M). The catalytic activity of Ni12P5 is likely to be correlated with the charged natures of Ni and P. Ni12P5 nanoparticles were introduced to silicon nanowires, and the power conversion efficiency of the resulting composite is larger than that of silicon nanowires decorated with platinum particles. This result demonstrates the promising application potential of metal phosphide in photoelectrochemical hydrogen generation.Keywords: electrocatalyst; electrolysis; hydrogen generation; nickel phosphide; photoelectrolysis; silicon nanowires
Co-reporter:Zhipeng Huang, Zhongzhong Chen, Zhibo Chen, Cuncai Lv, Mark G. Humphrey, Chi Zhang
Nano Energy 2014 Volume 9() pp:373-382
Publication Date(Web):October 2014
DOI:10.1016/j.nanoen.2014.08.013
•A convenient method is used to fabricate cobalt phosphide (Co2P) nanorods.•Co2P nanorods exhibit efficient electrocatalytic activity in hydrogen evolution reaction.•Co2P nanorods work stably in both acidic and basic solutions.Cobalt phosphide (Co2P) nanorods are found to exhibit efficient catalytic activity for the hydrogen evolution reaction (HER), with the overpotential required for the current density of 20 mA/cm2 as small as 167 mV in acidic solution and 171 mV in basic solution. In addition, the Co2P nanorods can work stably in both acidic and basic solution during hydrogen production. This performance can be favorably compared to typical high efficient non-precious catalysts, and suggests the promising application potential of Co2P nanorods in the field of hydrogen production. The HER process follows a Volmer–Heyrovsky mechanism, and the rates of the discharge step and desorption step appear to be comparable during the HER process. The similarity of charged natures of Co and P in the Co2P nanorods to those of the hydride-acceptor and proton-acceptor in highly efficient Ni2P catalysts, [NiFe] hydrogenase, and its analogues implies that the HER catalytic activity of the Co2P nanorods might be correlated with the charged natures of Co and P.
Co-reporter:Zhipeng Huang, Peng Zhong, Chifang Wang, Xuanxiong Zhang, and Chi Zhang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 6) pp:1961
Publication Date(Web):February 22, 2013
DOI:10.1021/am3027458
The top of silicon nanowires (SiNWs) arrays was coated with reduced graphene oxide (rGO) by the facile spin-coating method. The resulting SiNWs/rGO composite exhibits enhanced photoelectrochemical properties, with short-circuit photocurrent density more than 4 times higher than that of the pristine SiNWs and more than 600 times higher than that of planar Si/rGO composite. The trapping and recombination of photogenerated carriers at the surface state of SiNWs were reduced after the application of rGO. The results of electrochemical impedance spectroscopy measurements suggest that the reduction of trapping and recombination of photogenerated carriers as well as remarkably enhancement of photoelectrochemical properties can be attributed to the low charge transfer resistance at the SiNWs–rGO interface and rGO–electrolyte interface. The method and results shown here indicate a convenient and applicable approach to further exploitation of high activity materials for photoelectrochemical applications.Keywords: graphene; nanowires; photocatalyst; photoelectrochemisty; silicon;
Co-reporter:Zhipeng Huang, Chifang Wang, Lei Pan, Feng Tian, Xuanxiong Zhang, Chi Zhang
Nano Energy 2013 Volume 2(Issue 6) pp:1337-1346
Publication Date(Web):November 2013
DOI:10.1016/j.nanoen.2013.06.016
•A high efficiency and low-cost photocathode for hydrogen production is demonstrated.•Composite of silicon nanowires and molybdenum sulfide can be fabricated by a convenient method.•Electrochemical measurements reveal the origin of enhancement in photoelectrochemical performance.The composite of silicon nanowires (SiNWs) and MoS3 (SiNWs@MoS3) was fabricated by a convenient method. In comparison with SiNWs, SiNWs@MoS3 exhibits remarkably enhanced photocurrent during photoelectrochemical hydrogen production. The photoelectrochemical performance of SiNWs@MoS3 is comparable to that of the composite of SiNWs and Pt nanoparticles (SiNWs@PtNPs). Electrochemical impedance spectroscopy experiments suggest that the enhanced performance of SiNWs@MoS3 can be attributed to small charge transfer resistance (i.e. fast H+ reduction kinetics ) at SiNWs@MoS3/electrolyte interface, and the large electrochemically active surface area of SiNWs@MoS3.High efficient silicon nanowires (SiNWs)@MoS3photocathode was fabricated by a convenient method. The SiNWs@MoS3 exhibit remarkably enhanced photoelectrochemical hydrogen production, in comparison with the pristine silicon nanowires. The hydrogen production capability of silicon nanowires@MoS3 is also comparable to that of SiNWs@Pt nanoparticles. The superior photoelectrochemical hydrogen production ability of SiNWs@MoS3 can be ascribed to small charge transfer resistance (i.e. faradic reaction kinetics) at SiNWs@MoS3/electrolyte interface and large photoelectrochemical active area of SiNWs@MoS3.
Co-reporter: Zhipeng Huang;Lei Pan;Peng Zhong;Maoying Li; Feng Tian; Chi Zhang
Chemistry - A European Journal 2013 Volume 19( Issue 5) pp:1732-1739
Publication Date(Web):
DOI:10.1002/chem.201202462
Abstract
A facile method for the low-cost and large-scale production of ultralong Ag2S (or Ag2Se)ZnSe quantum wires has been developed. ZnSe quantum wires (diameter≈4 nm) with high uniformity in their crystal structure and diameter can be synthesized by using a catalyst-assisted growth approach with Ag2S nanoparticles as a catalyst. The influence of the growth temperature, time, and type of catalytic particle on the morphology of the ZnSe quantum wires was systematically explored. Besides Ag2S, Ag2Se nanoparticles can also be adopted as the catalyst for the growth of ZnSe wires. This method can also be applied to the fabrication of uniform CdSe nanorods. This method is convenient for the controllable fabrication of metal selenides and is of importance for exploring fundamental nanoscale semiconductor physics, as well as for affording technological devices with optimized characteristics.
Co-reporter:Zhipeng Huang, Ruxue Wang, Ding Jia, Li Maoying, Mark G. Humphrey, and Chi Zhang
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 3) pp:1553
Publication Date(Web):February 13, 2012
DOI:10.1021/am201758z
A facile method for the low-cost and large-scale production of silicon nanowires has been developed. Silicon powders were subjected to sequential metal plating and metal-assisted chemical etching, resulting in well-defined silicon nanowires. The morphology and structure of the silicon nanowires were investigated, revealing that single-crystal silicon nanowires with average diameters of 79 ± 35 nm and length more than 10 μm can be fabricated. The silicon nanowires show excellent third-order nonlinear optical properties, with a third-order susceptibility much larger than that of bulk silicon, porous silicon, and silicon nanocrystals embedded in SiO2.Keywords: etching; nonlinear optics; silicon nanowire; synthesis;
Co-reporter:Maoying Li, Ruxue Wang, Peng Zhong, Xiukai Li, Zhipeng Huang, Chi Zhang
Materials Letters 2012 80() pp: 138-140
Publication Date(Web):
DOI:10.1016/j.matlet.2012.04.109
Co-reporter:Zhipeng Huang;Nadine Geyer;Peter Werner;Johannes de Boor;Ulrich Gösele
Advanced Materials 2011 Volume 23( Issue 2) pp:285-308
Publication Date(Web):
DOI:10.1002/adma.201001784
Abstract
This article presents an overview of the essential aspects in the fabrication of silicon and some silicon/germanium nanostructures by metal-assisted chemical etching. First, the basic process and mechanism of metal-assisted chemical etching is introduced. Then, the various influences of the noble metal, the etchant, temperature, illumination, and intrinsic properties of the silicon substrate (e.g., orientation, doping type, doping level) are presented. The anisotropic and the isotropic etching behaviors of silicon under various conditions are presented. Template-based metal-assisted chemical etching methods are introduced, including templates based on nanosphere lithography, anodic aluminum oxide masks, interference lithography, and block-copolymer masks. The metal-assisted chemical etching of other semiconductors is also introduced. A brief introduction to the application of Si nanostructures obtained by metal-assisted chemical etching is given, demonstrating the promising potential applications of metal-assisted chemical etching. Finally, some open questions in the understanding of metal-assisted chemical etching are compiled.
Co-reporter:Zhipeng Huang, Tomohiro Shimizu, Stephan Senz, Zhang Zhang, Nadine Geyer and Ulrich Gösele
The Journal of Physical Chemistry C 2010 Volume 114(Issue 24) pp:10683-10690
Publication Date(Web):May 27, 2010
DOI:10.1021/jp911121q
Assisted by noble metal particles, non-(100) Si substrates were etched in solutions with different oxidant concentrations at different temperatures. The etching directions of (110) and (111) Si substrates are found to be influenced by the concentration of oxidant in etching solutions. In solutions with low oxidant concentration, the etching proceeds along the crystallographically preferred ⟨100⟩ directions, whereas the etching occurs along the vertical direction relative to the surface of the substrate in solutions with high oxidant concentration. These phenomena are found for both n- and p-type substrates as well as in experiments with different oxidants. The experiments on metal-assisted chemical etching are complemented by additional experiments on metal-assisted electrochemical etching of (111) Si substrates with different current densities. As a function of current density, a change of etching directions is observed. This shows that the change of the etching directions is mainly driven by the oxidation rate. On the basis of these phenomena, we have demonstrated fabrication of Si nanopores with modulated orientations by periodically etching a (111) substrate in solutions of low and high oxidant concentrations.
Co-reporter:Hee Han, Zhipeng Huang, Woo Lee
Nano Today (June 2014) Volume 9(Issue 3) pp:271-304
Publication Date(Web):1 June 2014
DOI:10.1016/j.nantod.2014.04.013
•This review provides the most recent developments of MACE of Si for controlled fabrication of nanostructured Si.•Etching mechanisms and the factors governing the etching behaviors and morphology of SiNWs are discussed.•Nanotechnology applications of MACE-formed SiNWs and challenges are discussed.Silicon nanostructures exhibit promising application potentials in many fields in comparison with their bulk counterpart or other semiconductor nanostructures. Therefore, the exploiting of controllable fabrication methods of silicon nanostructures, and the exploring of further applications of silicon nanostructures gain extensive attentions. In this review, recent advances in metal-assisted chemical etching of silicon, a low-cost and versatile method enabling fine control over morphology feature of silicon nanostructures, are summarized. The overview concerning the applications of silicon nanostructures in the field of energy conversion and storage, and sensors are also presented.Download high-res image (134KB)Download full-size image
Co-reporter:Zhipeng Huang ; Chifang Wang ; Zhibo Chen ; Hua Meng ; Cuncai Lv ; Zhongzhong Chen ; Ruqu Han ;Chi Zhang
ACS Applied Materials & Interfaces () pp:
Publication Date(Web):
DOI:10.1021/am501940x
Tungsten sulfides, including WS2 (crystalline) and WS3 (amorphous), were introduced to silicon nanowires, and both can promote the photoelectrochemical hydrogen production of silicon nanowires. In addition, more enhancement of energy conversion efficiency can be achieved by the loading of WS3, in comparison with loading of WS2. Polarization curves of WS3 and WS2 suggest that WS3 has higher catalytic activity in the hydrogen evolution reaction than WS2, affording higher energy conversion efficiency in silicon nanowires decorated with WS3. The higher electrocatalytic activity of WS3 correlates with the amorphous structure of WS3 and larger surface area of WS3, which result in more active sites in comparison with crystalline WS2.
Co-reporter:Cuncai Lv, Zhibo Chen, Zhongzhong Chen, Bin Zhang, Yong Qin, Zhipeng Huang and Chi Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 34) pp:NaN17675-17675
Publication Date(Web):2015/07/24
DOI:10.1039/C5TA03438H
Iron phosphide (FeP) was introduced onto silicon nanowires (SiNWs) via precursor loading and phosphorization. The resultant SiNWs/FeP shows remarkably enhanced photoelectrochemical hydrogen production in comparison with bare SiNWs. The solar power conversion efficiency of SiNWs/FeP is as high as 2.64%, which is 94% of that of SiNWs modified with Pt particles, and is larger than those of silicon-based photocathodes loaded with other non-precious electrocatalysts such as transition metals and their chalcogenides. The faster reaction rate of the hydrogen evolution reaction (HER) on the surface of the SiNWs/FeP than that of the bare SiNWs was confirmed by an electrochemistry impedance experiment (EIS). The investigations over the EIS spectra and the flat band potential show that the onset potential of cathodic photocurrent is mainly influenced by the reaction rate of the HER on the surface of the photocathode. The transient photocurrent experiments also suggest the faster kinetics of the HER on the surface of the SiNWs/FeP in comparison with that of the bare SiNWs. This result demonstrates a convenient approach to SiNWs loaded with a highly effective electrocatalyst and its promising application potential in photoelectrochemical hydrogen generation.
Co-reporter:Cuncai Lv, Zhen Peng, Yaoxing Zhao, Zhipeng Huang and Chi Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 4) pp:NaN1460-1460
Publication Date(Web):2015/12/22
DOI:10.1039/C5TA08715E
The development of an effective, non-precious electrocatalyst for the hydrogen evolution reaction (HER) is highly desirable for the commercial application of hydrogen as a clean and renewable energy and remains a substantial challenge. Herein, a hierarchical nanowires array (HNA) of iron phosphide (FeP) nanowires coated with iron phosphide nanorods grown on a carbon fiber paper (CFP) was constructed which exhibited remarkable catalytic activity in the HER. The overpotential required for the current density of 20 mA cm−2 is as small as 45 and 221 mV in acidic and basic solution, respectively, corresponding to Tafel slopes of 53 and 134 mV dec−1. The effective catalytic activity of the CFP–FeP HNA in the HER, together with its long-term stability and nearly 100% faradaic efficiency in water electrolysis, make the CFP–FeP HNA one of the best non-noble electrocatalysts described to date. The prominent catalytic activity of CFP–FeP HNA is correlated to the large number of active sites for the HER, and the fast electron transport from the CFP to the FeP nanorods mediated by FeP nanowires.
Co-reporter:Zhipeng Huang, Maoying Li, Ding Jia, Peng Zhong, Feng Tian, Zhongzhong Chen, Mark G. Humphrey and Chi Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 8) pp:NaN1426-1426
Publication Date(Web):2013/11/25
DOI:10.1039/C3TC31919A
Semiconductor–semiconductor hetero-nanorods (Ag2Se–CdSe and Ag2Se–ZnSe) with high crystallinity have been synthesized by a facile and low-cost method. High resolution transmission electron microscopy investigations reveal that the growth follows a catalyst-assisted mechanism. A preliminary investigation of nonlinear optical properties shows that the hetero-nanorods exhibit significantly enhanced third-order nonlinear optical properties. The free carrier absorption cross-section of Ag2Se–CdSe hetero-nanorods is one order of magnitude higher than that of the corresponding single component CdSe nanocrystals. The results obtained in this study represent a new approach to the design and construction of metal selenide hetero-nanorods with high crystallinity and enhanced nonlinear optical capabilities.
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