Interfacial dynamic hydroxyl flux mediated adsorbate-adsorbate interaction for efficient electrocatalytic 5-hydroxymethylfurfural oxidation

Abstract Electrocatalytic 5-hydroxymethylfurfural (HMF) oxidation (HMFOR) has been challenged by sluggish proton transfer and hydroxylation kinetics. Herein, SnO2 species were highly dispersed in glassified zeolite imidazole frameworks (ZIF) and sufficiently exposed to interface with CoOOH via glassification and electrochemical activation, creating an interfacial dynamic OH− flux at enriched CoOOH/SnO2 interfaces. The obtained CoSn(g) electrocatalyst shows a current density of 179.7mA cm−2 at 1.48V vs. reversible hydrogen electrode (RHE), along with 100% HMF conversion, 99.1% 2,5-furandicarboxylic acid (FDCA) yield, and 96.9% FDCA faradaic efficiency (FE). Impressively, with CoSn(g) as the anode, the integrated 5 × 5 cm2 membrane electrode assembly (MEA) electrolyzer remains above 93% FDCA yield for ten cycles at a 5 A industrial-scale current. Experimental and theoretical investigations demonstrate that the interfacial dynamic OH− flux mediates the adsorbate-adsorbate interactions, accelerating both the deprotonation and hydroxylation. Specifically, abundant *OH species anchored at Sn sites drive C–H/O–H bond cleavage in the intermediates on neighboring CoOOH and dynamically capture protons, thus facilitating the proton transfer process. Additionally, concentrated *OH at interfaces rapidly supplies OH− to adsorbed *HMF, facilitating hydroxylation. This work offers a fundamental understanding of microenvironment engineering via interfacial dynamic OH− flux for efficient biomass electrooxidation.