Advances and Challenges in the Doping Engineering of Nickel-Based Catalysts in the Urea Oxidation Reaction

The urea oxidation reaction (UOR) has shown significant application prospects in the field of urea-assisted hydrogen production in dealing with the nitrogen-containing wastewater. Nickel-based catalysts are the core system for catalyzing UOR, and doping engineering is widely used to enhance catalytic performance. In this context, we reviewed doping engineering to enhance nickel-based catalysts for UOR beyond the traditional classification based on element types. We first systematically elucidate the synergistic roles of doping-induced electronic-structure modulation, adsorption-energy optimization of key reaction intermediates, and regulation of lattice strain and defects along the UOR reaction pathway. The in situ doping and post-treatment doping strategies are integrated within the same analytical framework, enabling comparative discussions of their fundamental differences in dopant spatial distribution and active-site construction. From the perspective of dopant selection, the regulatory characteristics of nickel-based active centers and reaction interfaces are comprehensively reviewed across three dimensions of metal doping, non-metal doping, and synergistic co-doping. Finally, the problems and challenges for the catalysis mechanism understanding, the catalysts development, and the research trend are discussed. This review offers the advances in doping engineering of Nickel-based catalysts that would be helpful for catalyst development and novel catalyst design.