Pairing N‐Vacancy and Adjacent Ni‐Sites in the Local Microenvironment to Regulate the Urea Oxidation Reaction Pathway With Enhanced Kinetics

Abstract The urea oxidation reaction (UOR) is a promising approach for replacing the oxygen evolution reaction in hydrogen production, offering lower energy consumption. However, the kinetics of Ni‐based catalysts for UOR are hindered by the high formation potential of NiOOH and its repeated transition with Ni(OH) ₂ . In this study, a local microenvironment featuring electron‐deficient N‐vacancies (V _N ) paired with adjacent electron‐rich Ni‐sites on Ni ₃ N (Ni ₃ N‐V _N ) to enhance UOR kinetics is constructed. The electron‐rich Ni‐sites significantly reduce the energy barrier for NiOOH formation and promote the conversion of Ni(OH) ₂ to NiOOH. Meanwhile, the V _N sites induce low charge transfer resistance in Ni ₃ N, facilitating efficient electron transfer and boosting UOR performance while ensuring the stability of the active NiOOH phase. The V _N sites promote the adsorption of the urea N atom at the active site, favoring the reaction pathway toward “NCO⁻” formation without requiring complete urea dissociation. This pathway alleviates the NiOOH/Ni(OH) ₂ conversion cycle, lowers charge transfer resistance, and improves reaction kinetics. Ni ₃ N‐V _N demonstrates excellent UOR activity (low potential of 1.46 V at 1000 mA cm ⁻² ) and industrial prospects (integrating into an anion exchange membrane flow electrolyzer with 20% Pt/C, producing 600 mA cm ⁻² at 1.84 V), highlighting its potential for practical applications.