Theoretical Exploration of Anchoring Type Effects of C₂N Nanosheet-Supported Nickel Atoms for Urea Electrooxidation

Developing efficient nanosized electrocatalysts is crucial for driving the urea oxidation reaction (UOR) and conversion. Atomically dispersed metal atoms in two-dimensional materials have shown promising performance in various electrocatalytic reactions. However, the potential for UOR and the effect of anchoring type on their activity have not been fully explored. Herein, we designed two types of Ni atom-anchoring C2N electrocatalysts: doping (Ni-C2N) and adsorbing (Ni/C2N), and compared their UOR activities by density functional theory calculations. The investigation of the structural and electronic properties revealed the origin of the activity difference of both models. Consequently, Ni/C2N doped with Ni-N coordination bonds exhibited higher catalytic activity than that of the adsorbing sample due to its higher conductivity, favorable Ni-N coordination structure, and charge transfer with N-H-containing intermediates, hence enhancing the adsorption and dehydrogenation of key intermediates. Moreover, we demonstrated that the UOR activity can be further improved by introducing a second Ni atom to a hole in C2N. This study offers a valuable theoretical understanding of the design of atomically dispersed catalysts for efficient UOR.