Boosting surface reconstruction in engineered nickel sites through selenium vacancies to enhance urea oxidation reaction

Abstract

Designing an efficient electrocatalyst for the urea oxidation reaction (UOR) is not only favorable for the decomposition of urea contaminants in wastewater but also presents an environmentally friendly method for hydrogen generation. However, the competing oxygen evolution reaction (OER) at elevated current densities is a challenge as it limits the efficiency of the anode electrocatalysts. Herein, we propose the use of selenium-vacancy (Se_vac) engineering to boost the generation of metal (oxy)hydroxide on the surface of the nickel catalyst (Se_vac@NiSe-NS/NF) to enhance the electrocatalytic activity of UOR. The designed Se_vac@NiSe-NS displayed a potential of 1.61 V vs. RHE at 350 mA cm⁻² with robust durability at 500 mA cm⁻² for 40 h. Furthermore, when employed as an anode in a single-cell anion exchange membrane (AEM) electrolyzer, the Se_vac@NiSe-NS catalyst achieved a potential of 1.91 V at 100 mA cm⁻². In situ infrared reflection-absorption spectroscopy (IRRAS) reveals the molecular-level mechanisms behind the interfacial Se_vac@NiSe-NS sites in UOR.