Abstract: Photocatalytic technology with sunlight as driving force can convert solar energy into other energy sources for storage and further use. Cadmium sulfide (CdS), as a typical reducing semiconductor of metal sulfides, represents an interesting research hotspot in photocatalysis due to its suitable bandgap (2.4 eV) for utilizing visible light and strong reducing ability for inducing surface catalytic reactions. Unfortunately, the photocatalytic performance of CdS is still limited by its fast carrier recombination and serious photocorrosion. So far, CdS semiconductor has been widely developed as a typical reducing photocatalyst in constructing novel S-scheme heterojunction to overcome the above drawbacks. In this review, the design concepts, basic principles, and charge transfer characteristics of CdS-based S-scheme heterojunction photocatalysts have been comprehensively introduced. Several advanced and effective characterization methods for studying the mechanism of CdS-based S-scheme heterojunction are analyzed in detail. Furthermore, we also summarize the typical applications of CdS-based S-scheme heterojunctions for water splitting, CO₂ reduction, pollutant degradation, etc. Eventually, according to the current investigation status, some drawbacks in the current synthetic strategy, mechanism exploration, and application prospect of CdS-based S-scheme heterojunction are proposed, which need to be addressed by further expansion and innovative research.

Key words: Photocatalysis, CdS semiconductor, Heterojunction, S-scheme, Metal sulfide