Fluorine-induced dual regulation of Co(OH)₂ active sites and reactant adsorption behavior for boosted 5-hydroxymethylfurfural electrooxidation performance

Electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is pivotal for upgrading biomass to high-value bio-based monomers. However, this process is severely constrained by two critical challenges: insufficient catalytic active sites and the intrinsic competitive adsorption between HMF and OH−, which collectively restrict reaction kinetics and impede industrial scalability. Herein, we report a fluoride-assisted anodic electric field activation strategy that enables one-step synergistic integration of F− doping into the Co(OH)₂ lattice and electrochemical activation. This rational design yields F-doped Co(OH)₂/NF electrocatalysts with abundant Co3+/Ni3+ active species. The optimized catalyst exhibits a markedly enhanced HMF oxidation reaction (HMFOR) current density of 105 mA cm−2 at 1.5 V vs. RHE, corresponding to a 170% enhancement compared with pristine Co(OH)₂/NF, along with high 95% FDCA selectivity and excellent stability. Mechanistic investigations reveal that F doping exerts a dual regulatory effect: it not only facilitates the in-situ generation of reactive Co3+/Ni3+ active sites but also synergistically modulates the adsorption behavior of HMF and OH−. This synergism effectively mitigates adsorption competition and accelerates the rate-determining steps of HMFOR. Collectively, this work provides a new paradigm for the rational design of high-efficiency electrocatalysts via the synergistic regulation of active sites and adsorption properties, thereby laying a solid foundation for advancing the industrialization of sustainable biomass valorization.