A triple-functional Co2SnO4-enabled S-scheme heterojunction with photothermal promotion for efficient solar-driven hydrogen evolution

Abstract

Photocatalytic hydrogen production offers a sustainable route for solar energy conversion, yet its efficiency is hindered by rapid charge recombination, limited light absorption and slow reaction kinetics. In this study, we introduce a strategically engineered Co₂SnO₄@ZnIn₂S₄ S-scheme heterojunction photocatalyst that synergistically enhances charge separation, photothermal conversion and catalytic activity to overcome these challenges. Using a simple solvent self-assembly method, we develop a heterostructure in which Co₂SnO₄ nanoparticles serve as a versatile component by: (1) extending light absorption into the near-infrared (800–1400 nm) range for efficient solar-to-thermal conversion, (2) creating an S-scheme charge transfer pathway that enhances electron–hole separation while retaining high redox potentials, and (3) providing numerous active sites to accelerate proton reduction kinetics. The optimized photocatalyst achieves an impressive hydrogen evolution rate of 12.56 mmol g⁻¹ h⁻¹ and an apparent quantum efficiency of 12.96% at 420 nm. Comprehensive experimental and theoretical analyses validate the S-scheme charge transfer mechanism and quantify the photothermal and catalytic contributions to reaction enhancement. This work not only demonstrates a highly efficient photocatalytic system but also provides critical insights into designing multifunctional heterostructures for solar fuel generation, paving the way for practical renewable energy applications.