Pairing N-Vacancy and Adjacent Ni-Sites in the Local Microenvironment to Regulate the Urea Oxidation Reaction Pathway With Enhanced Kinetics.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40237240.
- Also identified by DOI 10.1002/adma.202503879 and PMC identifier 12272033.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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)<sub>2</sub>. In this study, a local microenvironment featuring electron-deficient N-vacancies (V<sub>N</sub>) paired with adjacent electron-rich Ni-sites on Ni<sub>3</sub>N (Ni<sub>3</sub>N-V<sub>N</sub>) 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)<sub>2</sub> to NiOOH. Meanwhile, the V<sub>N</sub> sites induce low charge transfer resistance in Ni<sub>3</sub>N, facilitating efficient electron transfer and boosting UOR performance while ensuring the stability of the active NiOOH phase. The V<sub>N</sub> 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)<sub>2</sub> conversion cycle, lowers charge transfer resistance, and improves reaction kinetics. Ni<sub>3</sub>N-V<sub>N</sub> demonstrates excellent UOR activity (low potential of 1.46 V at 1000 mA cm<sup>-2</sup>) and industrial prospects (integrating into an anion exchange membrane flow electrolyzer with 20% Pt/C, producing 600 mA cm<sup>-2</sup> at 1.84 V), highlighting its potential for practical applications.