Crystalline ZnO/ZnSxSe1−x core–shell nanowire arrays for efficient visible-light photoelectrocatalysis

Abstract

ZnO/ZnS_xSe_1−x core–shell nanowire arrays on a silicon substrate were successfully prepared via a hydrothermal method followed by chemical vapor deposition (CVD) of the ZnS_xSe_1−x shell. By optimizing the CVD growth conditions, a crystalline ZnS_xSe_1−x shell and well-aligned ZnO/ZnS_xSe_1−x interface were achieved, which plays an important role towards the enhanced performance of photocatalytic activity. The introduction of the crystalline, lattice-matched ZnS_xSe_1−x shell to ZnO nanowires significantly enhances the photocatalytic and photoelectrocatalytic activity under UV light irradiation. More attractively, after being combined with the ZnS_xSe_1−x shell, the visible light photoelectrocatalytic activity of the ZnO/ZnS_xSe_1−x core–shell nanowires is observed. The performance enhancement of ZnO/ZnS_xSe_1−x core–shell nanowires under irradiation is mainly due to matching lattice and band energy level alignment between the crystalline ZnS_xSe_1−x shell and ZnO nanowire core. The high crystal quality of the ZnS_xSe_1−x shell and the band alignment of the ZnO/ZnS_xSe_1−x core–shell greatly enhance the charge separation efficiency and prolong the life-time of photogenerated charge carriers. Our finding is expected to provide a new insight into the fabrication of novel and high performance nanowire based core–shell photocatalysts.