Autogenetic Carbon Oxyanions Enable Interfacial OH⁻ Deconfinement for Reinforced Biomass Electrooxidation over Wide Potential Window

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 V_RHE, 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.