Roles of sulfur-edge sites, metal-edge sites, terrace sites, and defects in metal sulfides for photocatalysis

Summary Metal-sulfide photocatalysts feature outstanding optoelectronic properties and suitable band-gap energy. Photocatalyst active sites, which are rationally designed, are very important for increasing the photocatalytic reaction rate. In this review, we classify the reactive sites of metal sulfides mainly into metal-edge sites, S-edge sites, terrace sites, and defects. We summarize recent research progress in the identification and characterization of reactive sites in metal sulfides, followed by recent synthesis methods for increasing the number of these reactive sites and adjusting their reactivity. A thorough understanding of the relationship between photocatalytic performance and reactive sites in metal sulfide is helpful for enhancing the activity and selectivity. Hence, we build different correlations between the active sites of metal sulfides and photocatalytic applications, including photocatalytic hydrogen production, CO2 reduction, pollutant decomposition, and N2 fixation. Finally, we discuss the opportunities and challenges for the development of active sites in metal sulfides in photocatalysis.