Constructing Hierarchical Wire-on-Sheet Nanoarrays in Phase-Regulated Cerium-Doped Nickel Hydroxide for Promoted Urea Electro-oxidation

Abstract

Electrocatalytic urea oxidation reaction (UOR) is a key half-reaction in assembling the direct urea fuel cells (DUFCs) to generate electricity, or constructing a urea electrolyzer to convert electricity to clean hydrogen energy. However, the sluggish six-electron transfer process of UOR significantly limits the reaction kinetics, thereby restricting the development of the aforementioned energy conversion techniques. Herein, we highlighted a high-performance UOR catalyst based on the hierarchical wire-on-sheet Ni(OH)2 nanoarrays with optimal cerium doping and controllable phase regulation. The local Ni3+ species and the unique wire-on-sheet morphology of the α-Ni(OH)2 nanoarray catalyst guarantee fast formation of high-valence species for UOR catalysis, and the Ce doping further optimizes the electronic structure, therefore resulting in greatly enhanced UOR behavior synergistically. This work may provide a universal structural optimization strategy for designing advanced UOR electrocatalysts.