Activating the (101) facets of Cu2WS4 in the CdS/Cu2WS4 S-scheme heterojunction to enhance the photocatalytic hydrogen evolution activity

Abstract

Exploring effective strategies to develop new and efficient photocatalysts for photocatalytic hydrogen evolution is of great significance for the development of hydrogen conversion technology. In this work, CdS particles were grown on Cu₂WS₄ by an in situ growth method, and a CdS/Cu₂WS₄ S-scheme heterojunction with strong redox ability was synthesized. It fully utilizes the large area (101) surface exposed by Cu₂WS₄ for catalytic reactions. CdS is dispersed on the surface of Cu₂WS₄, activating its (101) facet to consume photo-generated holes, thereby promoting charge carrier transfer. In addition, the introduction of Cu₂WS₄ not only provides a platform for CdS growth, but also constructs S-scheme heterojunctions between the contact interfaces, which is instrumental in the separation and migration of electron–hole pairs. Due to the synergistic effect of (101) facet activation and the S-scheme heterojunction, the CdS/Cu₂WS₄ heterojunction exhibits surprisingly high hydrogen evolution activity, which is 21.3 and 33.4 times higher than that of CdS and Cu₂WS₄, respectively. In addition, according to the basic experimental characterization and density functional theory calculations, the formation of the CdS/Cu₂WS₄ heterojunction effectively improves the separation efficiency of photogenerated electron–hole pairs, and thus enhances the photocatalytic redox performance. This work provides a strategy for designing and developing high-performance photocatalysts.