Surface reconstruction of Cu-Doped Ni(OH)2 during Electrolysis for enhanced urea oxidation

Abstract

In addressing the challenge posed by the substantial overpotential required by oxygen evolution reaction (OER), considerable attention has been directed toward urea oxidation reaction (UOR) as a promising alternative. This oxidation process reduces the energy input commonly linked to the excessive overpotential in OER and concurrently enables the elimination of urea from wastewater streams. These combined attributes indicate considerable promise for practical implementation in industrial contexts. Nickel (Ni)-based hydroxides have been widely recognized for their significant role in UOR. In this study, Cu doping was employed to enhance the valence state of Ni atoms in Ni(OH)₂, thereby facilitating the formation of Ni oxyhydroxide (NiOOH). The Cu-Ni(OH)₂ catalyst exhibited significantly enhanced catalytic activity in UOR compared to pure Ni(OH)₂. The synthesized catalysts exhibited exceptional performance in the urea oxidation reaction, achieving a low operational voltage of 1.283 V at a current density of 50 mA cm⁻², while also demonstrating impressive stability over extended periods, exceeding 150 h. The findings of this investigation offer valuable theoretical perspectives for the development of non-precious metal-based catalysts, which can efficiently promote surface reorganization during the reaction.