Construction and Nanoscale Detection of Interfacial Charge Transfer of Elegant Z-Scheme WO<sub>3</sub>/Au/In<sub>2</sub>S<sub>3</sub> Nanowire Arrays.

Li, Haijin; Gao, Yuying; Zhou, Yong; Fan, Fengtao; Han, Qiutong; Xu, Qinfeng; Wang, Xiaoyong; Xiao, Min et al. · Nano Lett · 2016

basic_science · Level V

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Abstract

Elegant Z-scheme WO<sub>3</sub>/Au/In<sub>2</sub>S<sub>3</sub> nanowire arrays were precisely constructed through a facile step-by-step route. Surface potential change on pristine or In<sub>2</sub>S<sub>3</sub>-Au coated WO<sub>3</sub> single nanowire under dark and illumination detected through a Kelvin probe force microscopy (KPFM) technique indicates that the vectorial holes transfer of In<sub>2</sub>S<sub>3</sub> → Au → WO<sub>3</sub> should occur upon the excitation of both WO<sub>3</sub> and In<sub>2</sub>S<sub>3</sub>. In such charge transfer processes, the embedded Au nanoparticles in the heterojunction systems act as a charge mediator for electrons in the conduction band of WO<sub>3</sub> and holes in the valence band of In<sub>2</sub>S<sub>3</sub>. The strong charge carrier separation ability of this structure will finally enhance the oxidation ability of WO<sub>3</sub> with high concertation of photogenerated holes and, further, leave the free electrons in the In<sub>2</sub>S<sub>3</sub> with long surviving time. Therefore, the unique Z-scheme WO<sub>3</sub>/Au/In<sub>2</sub>S<sub>3</sub> heterostructure shows great visible-light activity toward photocatalytic reduction of CO<sub>2</sub> in the presence of water vapor into renewable hydrocarbon fuel (methane: CH<sub>4</sub>).