Porous organic polymer-mediated oxygen-vacancy-rich MnO2-x/Cu2O composite enhances photocatalytic conversion of 5-hydroxymethylfurfural

5-Hydroxymethylfurfural (HMF) serves as a key platform molecule for green photocatalytic oxidation to produce high-value-added chemicals. Addressing the critical need for efficient photocatalytic conversion of HMF to 2,5-furan dicarboxylic acid (FDCA) under mild conditions, this study proposes and constructs a synergistic ternary composite photocatalytic system. By incorporating porous organic polymers (POPs) into oxygen-vacancy-rich MnO 2-x /Cu 2 O, the MnO 2-x @POPs@Cu 2 O composite photocatalyst was synthesized. This composite catalyst demonstrated remarkable photocatalytic performance under ambient conditions, achieving 71.8% conversion of HMF and 18.5% yield of FDCA. Results indicate that POPs not only selectively enrich reactants by forming dynamic imine bonds with HMF via its surface (–NH 2 ) functional groups, but also significantly enhance interfacial charge separation and transport through a locally embedded electric field generated by its highly negatively charged triazine framework, thereby accelerating the Mn-Cu bimetallic redox cycle. Furthermore, electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations confirmed that introducing POPs effectively reduces O 2 adsorption energy, promotes molecular oxygen activation, and enhances reactive oxygen species generation. This study provides a novel strategy for designing low-cost, high-efficiency multicomponent photocatalysts for biomass refining.