Step-scheme heterojunction photocatalyst: preparation, application and future outlook

Photocatalysis utilizes inexhaustible solar energy to provide a green and sustainable solution for environmental remediation and energy storage. The step-scheme (S-scheme) heterojunction was proposed to overcome the deficiencies of traditional type-II and Z-scheme heterojunctions in terms of kinetics and thermodynamics. This review aims to convey the state-of-the-art progress and achievements in the development of S-scheme heterojunctions. Firstly, the origins and fundamental principles of S-scheme heterojunctions were summarized. Secondly, the significant applications of S-scheme heterojunctions photocatalysts in hydrogen/hydrogen peroxide production, CO₂ reduction, pollutants degradation and bacteria disinfection were discussed. Thirdly, the facing challenges and prospects of S-scheme heterojunctions in industrial application were highlighted. At last, we proposed the future direction of researching S-scheme heterojunctions, including NIR absorption, interface engineering, co-catalysts, IT techniques and experimental robots, in order to provide novel insight for clean energy exploration and environmental issues treatment.