Defect Engineering of Nickel-Based Compounds for Energy-Saving H2 Production

The urea oxidation reaction (UOR), requiring less energy to produce hydrogen, is considered as a potential alternative to the traditional oxygen evolution reaction. Consequently, developing highly efficient UOR catalysts to facilitate H-2 production has garnered widespread attention. A promising approach to enhancing the effectiveness of these electrocatalysts is defect engineering. By introducing structural defects, defect engineering can expose more active sites and optimize their electronic structure, thereby improving their activity. This work offers a comprehensive overview of recent progress in defect engineering of nickel-based electrocatalysts for the UOR. It summarizes various strategies for generating defects, including the creation of vacancies, doping, the incorporation of single atoms, amorphization, and achieving high refractivity. Furthermore, we discuss the advanced characterization techniques commonly used to identify the presence of defects in these electrocatalysts, as well as to determine their detailed structures. Finally, we outline the prospects and challenges associated with the systematic design and fabrication of novel UOR electrocatalysts with tunable defects, aiming to further enhance their efficiency and stability.