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.

Metal-free carbon-based materials are considered as promising oxygen reduction reaction (ORR) electrocatalysts for clean energy conversion, and their highly dense and exposed carbon active sites are crucial for efficient ORR. In this work, two unique quasi-three-dimensional cyclotriphosphazene-based covalent organic frameworks (Q3CTP-COFs) and their nanosheets were successfully synthesized and applied as ORR electrocatalysts. The abundant electrophilic structure in Q3CTP-COFs induces a high density of carbon active sites, and the unique bilayer stacking of [6 + 3] imine-linked backbone facilitates the exposure of active carbon sites and accelerates mass diffusion during ORR. In particular, bulk Q3CTP-COFs can be easily exfoliated into thin COF nanosheets (NSs) due to the weak interlayer π–π interactions. Q3CTP-COF NSs exhibit highly efficient ORR catalytic activity (half-wave potential of 0.72 V vs. RHE in alkaline electrolyte), which is one of the best COF-based ORR electrocatalysts reported so far. Furthermore, Q3CTP-COF NSs can serve as a promising cathode for Zn-air batteries (delivered power density of 156 mW cm^–2 at 300 mA cm^–2). This judicious design and accurate synthesis of such COFs with highly dense and exposed active sites and their nanosheets will promote the development of metal-free carbon-based electrocatalysts.