Effective promotion of spacial charge separation in direct Z-scheme WO3/CdS/WS2 tandem heterojunction with enhanced visible-light-driven photocatalytic H2 evolution

Efficient charge separation and high photo-stability are crucial for sustainable solar-to-hydrogen energy conversion over photocatalysts. Here we describe a facile synthetic strategy to construct the novel direct Z-scheme tandem heterojunction consisting of the zero-dimensional (0D) ultrafine cadmium sulfide (CdS) nanograins and the two-dimensional (2D) ultrathin tungsten trioxide/tungsten disulfide (WO3/WS2) nanoplate matrixes. The WS2 co-catalyst combined with the direct Z-scheme electron transfer channels in WO3/CdS interfacial junctions facilitate the spatial separation and directional migration of photo-excited charge carriers. This smart design enables the optimized Z-scheme WO3/CdS/WS2 hybrid exhibit a high photocatalytic H-2 evolution activity of 14.34 mmoL.h(-1).g(-1) and an outstanding apparent quantum efficiency of 22.96% at 435 nm.