Theoretical study of electrocatalytic urea synthesis through CO₂ and N₂ on metal cluster decorated C₂N

The electrocatalytic C–N bond coupling of N₂ and CO₂ for urea production is an energy-efficient and eco-friendly alternative in industry. However, the remarkable stability of the inert gases and potential competing reduction reactions in electrocatalytic processes lead to low activity and selectivity. So, searching for low-cost electrocatalysts with high activity and selectivity for urea formation is very vital. Herein, by density functional theory calculations, we have systematically studied the process of electrocatalytic N₂ and CO₂ coupling for urea production on monolayer C₂N matrix containing chromium transition metal clusters (Cr₃@C₂N). Our calculational results reveal that N₂ and CO₂ can be chemically adsorbed and activated on Cr₃@C₂N and the formation of ^*NCON intermediate that is a key precursor for urea generation is exothermic. The limiting potential of urea formation is − 0.72 V. Meanwhile, the competing reactions, such as nitrogen reduction reaction and hydrogen evolution reaction have also been considered, which demonstrate the reaction of urea formation is predominant. To sum up, the Cr₃@C₂N possesses high activity and selectivity toward the electrosynthesis of urea, providing a new ideal for designing catalysts for C–N coupling electrochemical reactions.