S-scheme heterojunction photocatalysts for CO2 reduction

Step-scheme (S-scheme) heterojunctions have been widely applied in photocatalytic CO2 reduction because they facilitate the spatial separation of photogenerated carriers and maximize the redox powers of photocatalysts. The S-scheme heterojunction promotes the recombination of useless photogenerated charge carriers and preserves the useful ones for photocatalytic redox reactions. Various popular photocatalysts, such as metal oxides, metal chalcogenides, graphitic carbon nitrides, and bismuth oxyhalides, have been used to construct S-scheme heterojunctions and displayed improved CO2-reduction performance. To summarize the recent advances in this burgeoning field, this review discusses popular photocatalyticmaterials to constitute S-scheme heterojunctions for CO2 reduction. In the review, the fundamentals of S-scheme photocatalytic mechanisms are introduced. Then, the influence of S-scheme heterojunctions and selected photocatalysts on promoting photocatalytic CO2 reduction are highlighted. Lastly, challenges and prospects are discussed to motivate future studies on developing novel, high-performance S-scheme photocatalysts and studying the corresponding photocatalytic mechanisms.