Oxygen Vacancy-Mediated Tetrahedral–Octahedral Electron Relay in Zn _0.3 Cu _0.7 Co ₂ O ₄ Spinel for Selective Photo-Thermal Synergized Catalytic Oxidation of 5-Hydroxymethylfurfural

For the enhanced development of biodegradable plastics, developing efficiently nonprecious metal catalysts for selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is crucial. Herein, the study successfully constructed high-concentration oxygen vacancies (OV) in the Zn0.3Cu0.7Co2O4 spinel by regulating the heterogeneity ratio of Zn/Cu. The experimental results showed that its catalytic performance was comparable to that of the reported studies in the same system. Meanwhile, compared to the traditional thermal catalytic system using spinel, the Zn0.3Cu0.7Co2O4 catalyst in our photothermal synergized system exhibited a 3-fold increase in conversion and a 4-fold enhancement in selectivity at mild temperatures. Both experimental and theoretical studies reveal that the heterogeneity ratio of Zn/Cu can promote the formation of the OV and CuTd-OV-CoOh electron bridge construction. This deliberately designed structure promotes proton-coupled charge separation and electron transfer. These processes are facilitated separately by photoexcitation (via the interaction between CuTd and ZnTd) and thermal activation (via the CuTd-OV-CoOh electron bridge). In situ characterization confirms that the presence of OV facilitates the generation of active oxygen species, while DFT calculations demonstrate reduced energy barriers for key oxidation steps (HMFCA → FFCA). The work provides a strategic design for dual-functional spinel catalysts through targeted heterogeneity in the CuTd-OV-CoOh electron bridge, advancing photothermal effect mechanisms for biomass conversion.