Nanostructured Metal Sulfides: Classification,Modification Strategy,and Solar-Driven CO2 Reduction Application

Solar-driven conversion of CO₂ into high value-added fuels is expected to be an environmental-friendly and sustainable approach for relieving the greenhouse gas effect and countering energy crisis. Metal sulfide semiconductors with wide photoresponsive range and favorable band structures are suitable photocatalysts for CO₂ photoreduction. This review summarizes the recent progress on metal sulfide semiconductors for photocatalytic CO₂ reduction. First, the fundamentals, mechanisms and some principles, like product selectivity, of photocatalytic CO₂ reduction are introduced. Then, according to the elemental composition, the metal sulfide photocatalysts applied for CO₂ reduction are classified into binary (CdS, ZnS, MoS₂, SnS₂, Bi₂S₃, In₂S₃,Cu₂S, NiS/NiS₂, and CoS₂), ternary (ZnIn₂S₄, CdIn₂S₄, CuInS₂, Cu₃SnS₄, and CuGaS₂), and quaternary (Cu₂ZnSnS₄) systems, in which their crystal structures, photochemical characteristics, and photocatalytic CO₂ reduction applications are systematically demonstrated. Especially, the diverse modification strategies for improving the activity and product selectivity of photocatalytic CO₂ reduction on these metal sulfides are summarized. Finally, the current challenges and future directions for the development of metal sulfide photocatalysts for CO₂ reduction are proposed. This review is expected to serve as a powerful reference for exploiting high-efficiency metal sulfide photocatalysts for CO₂ conversion and furthering related mechanism understanding.