Urea oxidation catalysts: a review on non-metallic enhancements in nickel-based electrocatalysts

The urea oxidation reaction (UOR) offers a promising low-energy alternative to the conventional oxygen evolution reaction (OER) in hydrogen production, leveraging urea's lower thermodynamic barrier to reduce energy demands of water splitting. This review focuses on the design and optimization of nickel-based UOR catalysts through the strategic incorporation of nonmetallic inorganic dopants to enhance their electrocatalytic performance. By modulating the electronic structure and surface active sites, these dopants aim to improve catalytic activity. Specifically, this review examines the influence of nitrogen, phosphorus, boron, sulfur, selenium, and fluorine incorporation on the catalyst's structure and performance, considering various doping methodologies and their impact on active site exposure, adsorption energies, and reaction pathways. The study also discusses the challenges in maintaining catalyst stability and the complexity of the UOR mechanism, proposing future research directions and development pathways in the field of hydrogen energy.