Visible-light-driven valorization of 5-hydroxymethylfurfural over a hollow Co3O4@Zn3In2S6 nanocage in base-free water under an 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 molecule for pharmaceuticals and heterocyclic ligands, is extremely challenging under green and mild conditions. Herein, we construct a hollow Co₃O₄@Zn₃In₂S₆ (ZC–x) nanocage photocatalyst, which exhibits a remarkable photocatalytic activity for the oxidation of HMF to DFF in base-free water under an air atmosphere. The optimal ZC-5 heterojunction achieves 95.4% HMF conversion and 94.1% DFF selectivity. The superior photocatalytic performance of the ZC-5 heterojunction is attributed to intimate interfacial contact between Co₃O₄ 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 conditions.