Rational engineering design of nickel hydroxides for urea oxidation reaction: A mini-review

Nickel hydroxide (Ni(OH)2) are promising catalysts for efficient urea oxidation reactions (UOR), which can address the energy and environmental concerns associated with urea-containing wastewater. In addition to their low thermodynamic potential, this reaction can be used for energy-saving hydrogen production instead of the traditional oxygen evolution reaction. However, the sluggish kinetics and complex six-electron transfer process severely hamper the electrocatalytic performance of Ni(OH)2 electrocatalysts. To overcome those challenges, various strategies such as morphological design, heteroatom doping, surface vacancy, heterostructure, and supporting materials for Ni(OH)2 in UOR have been explored. This comprehensive summary highlights the significant research efforts in utilizing Ni(OH)2 for urea electrooxidation. The current challenges and prospects of Ni(OH)2 in UOR are also discussed, aiming to inspire further exploration in achieving efficient urea conversion.