pH-Dependent Urea Electrooxidation: From Mechanism to Catalysts and Applications.

Abstract

The urea oxidation reaction (UOR) serves as a pivotal process for sustainable wastewater remediation and renewable energy conversion, yet its practical implementation faces pH-dependent challenges that demand systematic understanding. This review comprehensively examines UOR mechanisms across alkaline, neutral, and acidic electrolytes, elucidating fundamental correlations between pH environments, catalytic activity, and reaction pathways. While alkaline media enhance kinetics via adsorbate evolution mechanisms, they often induce catalyst structural reconstruction that undermines stability; conversely, neutral and acidic media suffer from kinetic limitations due to inefficient proton-coupled electron transfer processes. Based on these insights, this review outlines several key optimization strategies for catalyst development, tailored to each pH environment, and explores the potential for scaling up alkaline UOR for energy-related applications. Finally, several critical future research directions that provide a roadmap for overcoming existing limitations and advancing UOR toward practical applications are proposed, which can serve as a timely framework for future developments in pH-tailored UOR systems of both environmental and energy sectors.