Dynamic Regeneration of Catalytic Sites on V-Modified NiCo Oxide for Boosting Urea Electrooxidation

Abstract

Nickel-based electrocatalysts have emerged as promising candidates for the urea oxidation reaction (UOR) in alkaline media. However, their active site availability is hindered by catalyst dissolution and inadequate surface active sites during the reaction. Here, we report the construction of stable high-valence V sites in a nickel cobalt vanadate catalyst (NiCoVO_x) for boosted UOR performance. After prolonged urea electrolysis, the catalyst structure and composition remain stable with suppressed V dissolution. In situ spectroscopies reveal that the V atoms directly act as active sites to interact with OH^– alongside the urea adsorption sites on Ni, which facilitate the C–N cleavage step of urea dehydrogenation. Accordingly, the Ni–V dual sites lead to accelerated UOR kinetics and stabilized valence state of Ni, thereby providing dynamically available active and UOR selective sites. As a result, the UOR on NiCoVO_x is obviously promoted with a 460 mV lower overpotential at 100 mA cm^–2 and 88% Faradaic efficiency for nitrogen-containing products. This work provides insights into the rational design of catalysts for multielectron small molecule electrooxidation reactions.