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

Abstract

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, CO 2 reduction, pollutant decomposition, and N 2 fixation. Finally, we discuss the opportunities and challenges for the development of active sites in metal sulfides in photocatalysis. Metal sulfides have competitive advantages over other traditional photocatalysts, including solar spectral response and electrical properties. Rational design and modulation of active sites in metal sulfides leads to improved efficiency for photocatalysis. Herein, we summarize the active sites of metal sulfides, including metal-edge sites, S-edge sites, terrace sites, and defects. In view of enhancing catalytically active sites, we discuss recent synthesis methods for increasing the number of reactive sites and adjusting reactivity. We build correlations between the active sites of metal sulfides and different photocatalytic applications. To inspire more research innovations, future research opportunities could include (1) the synthesis and application of single-atom-based metal sulfides, (2) the quantification and visualization of individual types of active sites during photocatalytic applications, and (3) the exploration of metal sulfides for practically usable products. This review summarizes the active sites of metal sulfides, including into metal-edge sites, S-edge sites, terrace sites, and defects. In view of enhancing catalytically active sites, recent synthesis methods for increasing the number of reactive sites and adjusting reactivity are also discussed. Different correlations are then been built between the active sites of metal sulfides and photocatalytic applications. More inspiring research involving synthesis, quantification and visualization, and practical applications in the field of metal-sulfide-based photocatalysis is also discussed.