Modulated D-Electron Transfer in Hypervalent Cobalt-Based Electrocatalyst for Efficient 5-Hydroxymethylfurfural...

5-hydroxymethylfurfural (5-HMF) electrooxidation is important in producing biomass-based valuable chemicals, whereas the preferential adsorption of only hydroxymethyl or formyl on a specific catalyst limits the reaction efficiency. Herein, the electrochemical synthesis of copper incorporated CoOOH electrocatalyst is reported that can execute the synchronized adsorption of both groups. The catalyst works under a low applied potential of 1.36 V_RHE, achieving 100% HMF conversion, 100% furan dicarboxylic acid yield and 96.8% Faraday efficiency, with good stability, repeatability and variety in catalyzing furfural electrooxidation to furoic acid. This superior performance is attributed to Cu incorporation that reduces the bandgap of CoOOH by d-orbital electrons contributing more significantly near the Fermi level and adjusts the morphology through constructing smaller and more compact particles over granular or sheet-like motifs. The operando Raman characterization and theoretical calculations verify a strong interaction between 5-HMF and the Cu-integrated CoOOH catalyst, which is ascribed to the altered local charge density regions by Cu species and enables stable adsorption of both hydroxymethyl and formyl functional groups. This work lays foundation for a versatile and energy-efficient strategy for biorefinery, enabling seamless integration with green electricity-driven hydrogen production, while accelerating advancements in renewable energy and green chemistry.