Built-in electric field empowering dual lewis acid sites for efficient substrate selective adsorption to accelerate dehydrogenation kinetics in HMF electrooxidation

Electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) enables sustainable high-value chemical production and carbon neutrality, but its kinetics are impeded by sluggish dehydrogenation arising from multi-step proton-coupled electron transfers (PCET). Herein, a built-in electric field (BEF) is rationally engineered via a CuCo 2 O 4 /CeO 2 heterostructure. The BEF drives interfacial charge redistribution to optimize Lewis acid sites and enrich oxygen vacancies. Consequently, CuCo 2 O 4 /CeO 2 exhibits superior performance (10 mA cm −2 @ 1.30 V RHE ), achieving complete HMF conversion at 1.45 V RHE , with both FDCA yield and Faradaic efficiency reaching 98 %. It also demonstrates excellent practical applicability in an MEA reactor and generality for various organic substrates. Electrochemical analysis, in situ characterization and DFT calculations collectively confirm: BEF optimizes the electronic structure of Lewis acid sites, enhancing the selective adsorption of Lewis bases (OH - /HMF and other intermediates), triggering CuCo 2 O 4 surface reconstruction into CoOOH, simultaneously accelerating the cyclic turnover of CoOOH after chemically oxidizing HMF, promoting PCET, and thus enabling an efficient indirect oxidation pathway with lowered energy barriers. This work reveals the crucial role of rational BEF design in modulating Lewis acid sites and optimizing the “adsorption-activation-desorption” of substrates, providing a novel universal strategy for accelerating the PCET kinetics of the oxidation reactions of HMF and other complex nucleophiles.