The unique photocatalytic mechanism of S-scheme heterojunction can be used to study new and efficient photocatalysts.By carefully selecting semiconductors for S-scheme heterojunction photo-catalysts,it is possible to reduce the rate of photogenerated carrier recombination and increase the conversion efficiency of light into energy.Chalcogenides are a group of compounds that include sulfides and selenides(e.g.,CdS,ZnS,Bi2S3,MoS2,ZnSe,CdSe,and CuSe).Chalcogenides have at-tracted considerable attention as heterojunction photocatalysts owing to their narrow bandgap,wide light absorption range,and excellent photoreduction properties.This paper presents a thor-ough analysis of S-scheme heterojunction photocatalysts based on chalcogenides.Following an introduction to the fundamental characteristics and benefits of S-scheme heterojunction photocata-lysts,various chalcogenide-based S-scheme heterojunction photocatalyst synthesis techniques are summarized.These photocatalysts are used in numerous significant photocatalytic reactions,in-cluding the reduction of carbon dioxide,synthesis of hydrogen peroxide,conversion of organic matter,generation of hydrogen from water,nitrogen fixation,degradation of organic pollutants,and sterilization.In addition,cutting-edge characterization techniques,including in situ characterization techniques,are discussed to validate the steady and transient states of photocatalysts with an S-scheme heterojunction.Finally,the design and challenges of chalcogenide-based S-scheme het-erojunction photocatalysts are explored and recommended in light of state-of-the-art research.