Novel flower-like SnIn4S8/WO3 S-scheme heterojunction photocatalysts for enhanced oxidation of 5-hydroxymethylfurfural

We developed a chemically bonded SnIn 4 S 8 /WO 3 S-scheme heterostructure photocatalyst for solar-driven selective oxidation of HMF to DFF. The S-scheme charge transfer mechanism was confirmed by DFT calculations and experimental results, offering new insights for advancing photocatalytic biomass conversion. Solar biomass conversion has garnered significant research attention, but the rapid recombination of electrons and holes in photocatalysts hinders efficiency. To enhance this process, researchers aim to develop S-scheme heterojunction photocatalysts with optimized band structures that enable effective electron-hole separation, thereby improving overall efficiency. Herein, chemical-bonded SnIn 4 S 8 /WO 3 S-scheme heterostructure photocatalyst was constructed via in-situ hydrothermal strategy for sunlight-driven catalytic selective oxidization of 5-hydroxymethylfurfural (HMF) into valuable 2,5-dimethylfuran (DFF). X-ray photoelectron spectroscopy (XPS) results prove the formation of a W–S chemical bond in the composites, which will likely enhance the efficient transport of photogenerated charges. The optimal SnIn 4 S 8 /WO 3 exhibited an excellent HMF conversion rate (89%) and DFF yield (68%) after 2 h. The S-scheme charge transfer pathway in the SnIn 4 S 8 /WO 3 composite structure was verified through density functional theory (DFT) calculations and supported by partial in situ experimental results. This study demonstrates that the S-scheme heterostructure based on SnIn 4 S 8 offers innovative insights for advancing photocatalytic biomass conversion.