Construction of CoO–Cu₂O Composites with Enhanced HMF Adsorption and Passivated Water Oxidation for High-Efficiency Biomass Valorization

Abstract

Electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) to high-value-added products shows great promise for sustainable chemical production and reduced fossil resource utilization, yet exploring highly efficient HMFOR electrocatalysts with high current densities and Faraday efficiency (FE) remains a great challenge. Co-based catalysts could enable 5-hydroxymethylfurfural (HMF) oxidation at low potentials, but the slow kinetics as well as competing oxygen evolution reaction (OER) often results in low FE, especially under high current densities. Meanwhile, Cu-based catalysts with poor OER activities could achieve high FE for HMFOR but at the cost of low current densities. Herein, bimetallic Co-Cu oxide composites (CoO-Cu 2 O) are constructed to combine the advantages of both, while the synergistic effect between CoO and Cu 2 O could modulate oxygen vacancy (V O ) defects, boost electron transfer from Cu to Co species, which improves HMF adsorption and accelerate HMF conversion. Besides, the competitive OER is suppressed by Cu-based species with an apparent inhibitory effect. As a result, the optimized CoO–Cu 2 O composites achieve a remarkable current density of 355.7 mA cm –2 at 1.425 V vs RHE for HMFOR. Besides, nearly 100% of HMF conversion and a high FE FDCA of 99.6% are obtained. This work highlights the advantage of constructing transition bimetallic catalysts in synergistically improving HMFOR performance and provides new insights into the design of efficient catalysts.