Regulating the Local Charge Distribution of Ni Active Sites for the Urea Oxidation Reaction

Abstract

In electrochemical energy storage and conversion systems, the anodic oxygen evolution reaction (OER) accounts for large proportion of energy consumption. Electrocatalytic urea oxidation reaction (UOR) is one of the promising alternatives for OER, owing to its low thermodynamic potential. However, the sluggish UOR kinetics has not yet unlocked its potential in practical use. Herein, we developed a tungsten (W)‐introduced Nickel (Ni) based catalyst (Ni‐WO x ), which possessed superior activity towards UOR. The Ni‐WO x catalyst exhibited record fast reaction kinetics (440 mA·cm ‐2 at 1.6 V versus reversible hydrogen electrode) and high turnover frequency of 0.11 s ‐1 , which is 4.8 times higher than that without W dopants. Electrochemical studies, in‐situ X‐ray absorption spectroscopy and X‐ray photoelectron spectroscopy demonstrated that the W regulated the local charge distribution of Ni atoms, leading to the formation of Ni 3+ sites with superior activity and thus accelerating the interfacial catalytic reaction. Moreover, when we integrated Ni‐WO x into a CO 2 flow electrolyzer, the cell voltage is reduced to 2.16 V accompanying with ~98% Faradaic efficiency towards carbon monoxide, suggesting the great potential of high efficient UOR to enhance the CO 2 utilization and economic viability.