LAUSR

The preferential adsorption toward OH− on the anode most likely blocks the accessibility of organic molecules and triggers competitive oxygen evolution reaction (OER), typically precipitating a narrow potential window. Here, an OH− deconfinement strategy enabled by CO32− self‐transformed from C2O42− on metallic nickel oxalate (NiC2O4) for efficient synthesis of bioplastic monomer 2,5‐furanedicarboxylic acid (FDCA) with faradaic efficiency of >95% via electrocatalytic 5‐hydroxymethylfurfural (HMF) oxidation reaction (e‐HMFOR) at a wider potential window of 1.38–1.56 VRHE, outperforming state‐of‐the‐art Ni‐based electrocatalysts is presented. In situ, tests corroborate that the construction of NiOOH with surface‐adsorbed CO32− (NiOOH‐CO32−) from NiC2O4 can be facilitated by self‐liberating CO32−. The CO32− ions serving as an electric field engine can effectively weaken OH− coverage through electrostatic repulsion and enhance HMF adsorption at the NiOOH‐CO32− surface, thereby heightening e‐HMFOR while inhibiting OER. Computational results further indicate that the CO32− on NiOOH hoists the energy barrier of oxygen intermediate conversion (O* → OOH*) to suppress OER but promotes the e‐HMFOR kinetics. The precise modulation of OH− adsorption behavior on the electrocatalyst offers a powerful kit for boosting the oxidative upgrading process while circumventing the competing reaction OER.