Understanding Urea Oxidation Reaction Kinetics in Nickel Based Electrocatalysts

Abstract

This study investigates the electrochemical oxidation of urea on nickel electrodes in alkaline media. Using cyclic voltammetry (CV), the influence of urea concentration and applied potential on the redox transitions of Ni(OH)₂/NiOOH was explored. The results reveal that β-NiOOH is critical as a catalytic oxidant in the indirect oxidation mechanism, with increasing urea concentrations leading to suppression of the β-NiOOH reduction peak. Cathodic area analysis visualizes the extent of the suppression in the presence of urea. Fixed-potential analyses indicate kinetic inhibition at elevated concentrations due to surface saturation or adsorption effects. Kinetic modeling based on surface coverage supports a potential-dependent transition from electrochemical to chemically limited regimes. These findings provide a foundation for future optimization of nickel-based electrocatalysts for energy-efficient hydrogen production and urea-rich wastewater treatment.