Dual-sulfur-vacancy-enhanced interfacial electric field and photothermal effect for boosting selective photooxidation of 5-hydroxymethylfurfural

While photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) into valuable chemicals represents a crucial strategy for advancing carbon neutrality, low conversion rates and poor product selectivity hinder commercialization. In this study, a dual-sulfur-vacancy (S_v)-mediated Cu₂ZnSnS_4-x/ZnIn₂S_4-x all-multinary-sulfide p-n heterojunction was designed for high-efficiency photocatalysis. Specifically, S_v introduction significantly enhanced light absorption, photothermal properties, and interfacial electric fields (IEF). Consequently, the Cu₂ZnSnS_4-x/ZnIn₂S_4-x heterostructure achieved outstanding photothermal-assisted photocatalytic oxidation of HMF to 2,5-diformylfuran (DFF), with an oxidation rate of 94.1%, which was 9.1 and 4.0 times higher than that of Cu₂ZnSnS₄ and ZnIn₂S₄, respectively. The selectivity of DFF reached 92.8%. Additionally, mechanistic analysis identified primary active species and possible reaction pathways. This study provides a potential strategy for the design of photocatalytic systems for efficient HMF oxidation.