Electrochemical production of urea using triatomic cluster/C2N catalysts: A DFT study

Urea (NH₂CONH₂) plays a crucial role as both a nitrogen-based fertilizer and a key industrial raw material. Its conventional synthesis typically requires harsh conditions. In contrast, the electrocatalytic conversion of nitrogen (N₂) and carbon dioxide (CO₂) into urea has emerged as a promising alternative. However, achieving catalysts that offer both high activity and selectivity is still a huge challenge. This study utilizes density functional theory for investigating the electrochemical coupling between N₂ and CO₂ for the production of urea, specifically examining the performance of various transition metal clusters (from Groups IB and VIII) supported on C₂N catalysts. The results revealed that these catalysts demonstrate strong thermodynamic stability and effectively facilitate the co-adsorption of CO₂ and N₂. Notably, except Pd and Pt, most M₃/C₂N catalysts efficiently suppress the H 2 evolution reaction, preventing the excessive protonation of CO and the generation of ammonia, thus guaranteeing high selectivity for urea. In particular, Ru₃ and Os₃/C₂N catalysts demonstrate lower free energies and promote C-N coupling via *N₂ and *CO intermediates. Further evaluation of the electronic structure of Os₃/C₂N revealed an "acceptance-donation" mechanism that enhanced the activation of *CO₂ and *N₂, with the Os₃ cluster playing a crucial role. This research provides a new approach for electrochemically synthesizing urea and offers valuable insights into the design of advanced electrocatalysts. Electrochemical production of urea by using triatomic cluster/C 2 N catalysts. • The activity of M 3 /C 2 N SCCs for urea synthesis is studied based on DFT. • M 3 /C 2 N SCCs possess robust thermodynamic stability and the ability to co-adsorption CO 2 and N 2 . • Except for Pd and Pt, most M 3 /C 2 N catalysts exhibit high selectivity towards urea production. • The Os 3 /C 2 N SCC suggest an “acceptance-donation” mechanism for the activation of *CO 2 and *N 2 .