In-situ vulcanization enhances the two-dimensional interface effect and promotes carrier separation to achieve efficient photocatalytic hydrogen evolution

Abstract

The key to designing and synthesizing efficient composite photocatalysts is to regulate the relationship between the main catalyst and the co-catalyst and optimize the heterojunction. The heterojunction of composite photocatalysis can be optimized by adjusting the loading mode and morphology of the co-catalyst. Here, tungsten sulfide nanosheets (WS2 NS) were loaded on the surface of carbon nitride nanosheets (g-C3N4 NS) by in-situ vulcanization method, so as to form the in-situ composite photocatalyst (In-situ WS2/g-C3N4) with two-dimensional (2D) heterojunction. The hydrogen evolution efficiency of In-situ WS2/g-C3N4 at the optimal ratio is 219.9 μmol g−1 h−1, which is not only exceeds that of pure g-C3N4 NS but also is 5.8 times higher than that of physical composite photocatalyst (WS2/g-C3N4). The reason for enhancing photocatalytic activity is that WS2 NS, as a co-catalyst, can rapidly capture excited electrons in g-C3N4 NS, while in-situ loading of the co-catalyst optimizes the interaction of heterojunction and enhances the built-in electric field, enabling electrons to quickly migrate to the surface of the co-catalyst. The formation of 2D heterojunction can increase the contact area between catalysts, provide abundant reaction sites and electron transport channels, inhibit electron reflux, and improve the separation efficiency of photogenerated carriers. This study provides a new idea and theoretical basis for the design and development of platinum-like co-catalysts and the optimization of heterojunction.