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Construction of ZnO/ZnS/CdS/CuInS2 Core–Shell Nanowire Arrays via Ion Exchange: p–n Junction Photoanode with Enhanced Photoelectrochemical Activity under Visible Light

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journal contribution
posted on 11.06.2014, 00:00 by Yu-Xiang Yu, Wei-Xin Ouyang, Zhou-Ting Liao, Bin-Bin Du, Wei-De Zhang
ZnO/ZnS/CdS/CuInS2 core–shell nanowire arrays with enhanced photoelectrochemical activity under visible light were successfully prepared via ion exchange and hydrothermal methods. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis absorption, X-ray photoemission spectroscopy, and photoelectrochemical response. As a p–n junction photoanode, ZnO/ZnS/CdS/CuInS2 heterostructure shows much higher visible light photoelectrocatalytic activity toward water splitting than ZnO/ZnS/CdS and ZnO/ZnS films. The ZnO/ZnS/CdS/CuInS2 film with optimal constitution exhibits the highest photocurrent of 10.5 mA/cm2 and the highest IPCE of approximately 57.7% at 480 nm and a bias potential of 0 V versus Ag/AgCl. The critical roles of CdS and ZnS in ZnO/ZnS/CdS/CuInS2 heterostructure were investigated. ZnS, as a passivation layer, suppresses the recombination of the photogenerated charge carriers at the interface of the oxide and CuInS2. CdS enhances the absorption of visible light and forms p–n junctions with CuInS2, which promotes the transport of charge carriers and retards the recombination of electrons and holes in CuInS2 to improve the photoelectrochemical performance of ZnO/ZnS/CdS/CuInS2 heterostructure.