Morphological effects of WO3 in metal sulfide-based S-Scheme heterojunctions for boosting photocatalytic hydrogen production

Abstract

In the field of photocatalytic hydrogen production, metal sulfides are frequently utilized, particularly Cd sulfides, which have the benefits of a narrow band gap and a sufficient band gap. Other photocatalysts are required to enhance the situation because it still has a high photogenic carrier recombination rate and has flaws like photocorrosion that need to be fixed. The best morphology combination must be chosen since, as we are all aware, the morphology of the catalyst can significantly alter its activity. To choose the best morphology, we chose maple leaf CdS and WO3 with various morphologies to construct the S-Scheme heterojunctions, and WO3 was then applied to other metal sulfides. It is concluded that granular WO3–0D and CdS-F have the highest hydrogen evolution activity, which may indicate that 0D has the highest loading capacity and may play a certain supporting role for the catalyst that is easy to agglomerate, exposing more hydrogen evolution active sites to enhance hydrogen production. At the same time, the main hydrogen evolution active crystal face of the metal sulfide in the paper is (1 0 0) crystal face. When the crystal face is exposed, the metal sulfide in the paper has good hydrogen evolution activity, and the hydrogen evolution activity will be greatly reduced after the crystal face is covered. The established spatial angle between the (1 0 0) crystal face exposed by CdS-F and the (1 1 1) crystal face exposed by WO3–0D is large, so the highly active crystal face and active site are preserved as much as possible. On the other hand, WO3 decreases the recombination rate of electron-hole pairs in metal sulfide, resulting in a greater contribution of photogenerated electrons to the hydrogen evolution reaction. The Tafel clearly demonstrates the variation of hydrogen production rate control steps. This offers some suggestions for choosing the photocatalyst's morphological configuration.