Transition Metal-Based Catalysts for Urea Oxidation Reaction (UOR): Catalyst Design Strategies, Applications, and Future Perspectives

Urea oxidation reaction (UOR) has garnered significant attention in recent years as a promising and sustainable clean-energy technology. Urea-containing wastewater poses severe threats to the environment and human health. Numerous studies hence focus on developing UOR as a viable process for simultaneously remediating wastewater and converting it into energy. Moreover, UOR, which has a thermodynamic potential of 0.37 V (vs reversible hydrogen electrode, RHE), shows great promise in replacing the energy-intensive oxygen evolution reaction (OER; 1.23 V vs RHE). The versatility and stability of urea, particularly at ambient temperatures, make it an attractive alternative to hydrogen in fuel cells. Since UOR entails a complex intermediate adsorption/desorption process, many studies are devoted to designing cost-effective and efficient catalysts. Notably, transition metal-based materials with regulated d orbitals have demonstrated significant potential for the UOR process. However, comprehensive reviews focusing on transition metal-based catalysts remain scarce. In light of this, the review aims to bridge the gap by offering an in-depth and systematic overview of cutting-edge design strategies for transition metal-based catalysts and their diverse applications in UOR. Additionally, the review delves into the status quo and future directions, charting the course for further advancements in this exciting field. On the design, applications, challenges and solutions for urea oxidation reaction (UOR).image