A comprehensive review of S-scheme heterojunction photocatalysts for CO2 reduction: Design principles, mechanisms, and material classification

Abstract

CO₂, a major greenhouse gas emitted by industries, contributes to the greenhouse effect and global warming. The photocatalytic reduction of CO₂ into hydrocarbon fuels, such as methane or methanol, using sunlight has emerged as an effective strategy for mitigating environmental pollution and energy crisis. S-scheme heterojunction photocatalysts are particularly preferred for photocatalytic CO₂ reduction owing to their ability to enhance carrier separation and optimize redox potential. This paper provides a comprehensive review of the research progress on S-scheme heterojunction in photocatalytic CO₂ reduction, including their design principles, characterization methods, mechanisms, and influencing factors of this reaction. Common photocatalytic materials used to construct S-scheme heterojunctions for CO₂ reduction are summarized, including g-C₃N₄, TiO₂, ZnO, CdS, Znln₂S₄, and BiVO₄, metal-organic frameworks, and covalent organic frameworks. The impact of S-scheme charge-transfer pathways in these heterojunctions and the unique properties of the photocatalysts on the CO₂ reduction process are thoroughly elucidated.