Rational design of a novel quaternary ZnO@ZnS/Ag@Ag2S nanojunction system for enhanced photocatalytic H-2 production

Semiconductor photocatalysis provides a promising potential solution to the challenging issue of clean energy production. Construction of multijunction systems is an effective strategy to overcome the serious drawbacks of fast charge recombination and the limited visible-light absorption of semiconductor photocatalysts. Here, we report a novel quaternary heterogeneous photocatalyst fabricated by loading Ag nanoparticles onto ZnO nanowires and subsequent simultaneous formation of core/shell structured ZnO@ZnS and Ag@Ag2S heterojunctions via a one-step anion-exchange sulfuration reaction process. The resulting four-component ZnO@ZnS/Ag@Ag2S multijunction photocatalyst exhibits a high hydrogen evolution activity (140.3 mol g(-1)) under simulated solar light irradiation in 5 h, far exceeding those of bare ZnO (30.8 mol g(-1)), ZnO@ZnS (92.8 mol g(-1)) and ZnO/Ag (45.1 mol g(-1)) counterparts. The enhanced photocatalytic activity can be attributed to the synergetic effect of the formation of both Z-scheme and type II core/shell heterojunctions, favoring light absorption and separation of photogenerated electron-hole pairs in the composite. This work provides a facile, controlled method for the fabrication of multicomponent heterostructures used for efficient solar water splitting.