WS2 quantum dots/MoS2@WO3-x core-shell hierarchical dual Z-scheme tandem heterojunctions with wide-spectrum response and enhanced photocatalytic performance

A novel WS2/MoS2@WO3-x core-shell hierarchical dual Z-scheme tandem heterojunction photocatalyst is fabricated through two-step hydrothermal and heat-treatment strategy. The unique dual Z-scheme tandem heterojunction core-shell structure favors the transfer and spatial separation of photogenerated electron-hole pairs greatly, in which WO3-x serves as a bridge to connect two semiconductors and extends the photoresponse to visible light and NIR regions. The obtained core-shell structure tandem heterojunction exhibits excellent photothermal and photocatalytic performance, which is much better than that of any pristine ones. The excellent activity can be ascribed to the dual Z-scheme tandem heterojunction favoring transfer and spatial separation of photogenerated charge carriers, surface defect engineering (oxygen doping) extending photoresponse to long wavelength region and prolonging the lifetime of carriers, and the hierarchical structure offering massive surface active sites. In addition, the photothermal effect for the tandem heterojunction promotes the photocatalytic performance obviously.