Selective Oxidation of 5-Hydroxymethyl Furfural Coupled with H₂ Production over Surface Sulfur Vacancy-Rich Zn₃In₂S₆/Bi₂MoO₆ Heterojunction Photocatalyst

The construction of heterojunctions and surface defects is a promising strategy for enhancing photocatalytic activity. A surface sulfur vacancy (V-S)-rich Zn3In2S6/Bi2MoO6 heterojunction photocatalyst (ZIS-V-S/BMO) was herein developed for the selective oxidation of biomass-derived 5-hydroxymethyl furfural (HMF) to value-added 2,5-diformylfuran (DFF) coupled with H-2 production. The ZIS-V-S/BMO heterojunction consisted of Bi2MoO6 (BMO) with preferentially exposed high-index (131) facets and V-S-rich two-dimensional (2D) Zn3In2S6 (ZIS-V-S) nanosheets with preferentially exposed high-index (102) facets. The directional transfer of light-driven electrons from BMO to ZIS-V-S occurs in the heterojunction interface, as confirmed by an in situ irradiated XPS (ISI-XPS) measurement, which facilitates the electron-hole separation. The benefits of V-S in activating HMF, suppressing overoxidation of DFF, and accelerating electron transport were disclosed by molecular simulation. ZIS-V-S/BMO displays outstanding performance with a DFF yield of 74.1% and a DFF selectivity of 90%, as well as a rapid rate of H-2 evolution. This research would help design highly efficient photocatalysts and develop a new technology for biomass resource utilization.