Carbon‐Oxyanion Atomically Steering Direct Urea Oxidation on NiOOH at Industrial Current Densities

Abstract Developing cost‐effective electrocatalysts for the urea oxidation reaction (UOR) requires overcoming fundamental limitations of Ni‐based systems: sluggish Ni ²⁺ /Ni ³⁺ redox kinetics, competing oxygen evolution, and structural instability. Herein, we demonstrate an organic acid‐assisted electrochemical reconstruction strategy to synthesize carbon‐based oxyanion atomically modified β‐NiOOH nanosheets (Activated NiC ₂ O ₄ /NF) from nickel oxalate precursors. The in situ embedded oxyanions (‐CO _x ) confer triple functionality: 1) enabling direct urea oxidation at ultralow potentials (1.253 V@10 mA cm ⁻² , 1.357 V@2000 mA cm ⁻² in 6 m KOH + 0.33 m urea) bypassing NiOOH pre‐formation; 2) suppressing competing OER via a 0.23 eV thermodynamic penalty on the deprotonation evolution step; 3) enhancing lattice oxygen stability by increasing the oxygen vacancy formation energy. This synergy delivers record stability (3000 h@100 mA cm ⁻² ) and near‐unity N‐product selectivity (>95 ± 2% Faradaic efficiency). In a practical alkaline urea electrolyzer (6 m KOH + 0.33 M urea, 80 °C), it achieves 2000 mA cm ⁻² at 2.089 V, surpassing state‐of‐the‐art systems. Operando studies and DFT calculations reveal that in situ‐generated oxyanions not only promote UOR via an NH ₃ intermediate‐assisted pathway but also inhibit the oxygen evolution reaction by suppressing deprotonation evolution at the active sites. This work establishes a paradigm for anionic‐modification engineering in high‐current‐density electrocatalysis.