Visible-light-driven valorization of 5-hydroxymethylfurfural over a hollow Co₃O₄@Zn₃In₂S₆ nanocage in base-free water and air atmosphere

Abstract

Visible-light-driven upgrading of biomass-derived 5-hydroxymethylfurfural (5-HMF) represents a green and sustainable strategy. However, photocatalytic selective oxidation of HMF to generate 2,5-diformylfuran (DFF), a highly promising biomass-derived molecular for pharmaceuticals and heterocyclic ligands, is extremely challenging under green and mild condition. Herein, we construct a hollow Co3O4@Zn3In2S6 (ZC-x) nanocage photocatalyst, which exhibits a remarkable photocatalytic activity for HMF-to-DFF in base-free water and air atmosphere. The optimal ZC-5 heterojunction achieves 95.4% HMF conversion and 94.1% DFF selectivity. The superior photocatalytic performance of ZC-5 heterojunction is attributed to intimate interfacial contact betweenCo3O4 and Zn3In2S6, which is beneficial to generate strong interfacial interaction and facilitate the separation of electron-hole pairs. Characteristic analysis and density functional theory (DFT) calculations elucidate that the enhanced built-in electric field (IEF) and S-scheme charge transfer mechanism within the ZC heterojunction effectively drive the selective photo-oxidation of HMF-to-DFF. This work offers an efficient strategy to design heterojunction photocatalysts for highly effective oxidation of HMF under mild condition.