Metal sulfide-based Z-scheme heterojunctions in photocatalytic removal of contaminants, H₂ evolution and CO₂ reduction: Current status and future perspectives

Metal sulfides are promising photocatalysts in virtue of inherent photoelectric properties and wide light absorption range. However, metal sulfides are usually subjected to photocorrosion and high carrier recombination. The assembly of metal sulfide-based Z-scheme heterojunctions not only can overcome the above shortcomings of metal sulfides, but also maintain optimum redox performance. This review will provide an overview on the general properties of metal sulfides, three different types and synthesis methods of metal sulfide-based Z-scheme heterojunctions. Most importantly, the photocatalytic mechanism originating from the internal electric field was discussed from the Fermi level, direction of charge transfer and generation of reactive species. The applications of metal sulfide-based Z-scheme heterojunctions in decomposing organic contaminants, hydrogen (H₂) evolution and carbon dioxide (CO₂) reduction were also summed up. In the end, the challenges and outlooks of sulfide-based Z-scheme heterojunctions were presented.