Unveiling the key intermediates in electrocatalytic synthesis of urea with CO2 and N2 coupling reactions on double transition-metal MXenes

Abstract

The direct electrocatalytic synthesis of urea from nitrogen (N₂) and carbon dioxide (CO₂) under mild conditions is of great significance in promoting energy and environmental strategies. However, the current strategy operated under mild conditions suffers from many technical bottlenecks, such as a complex synthesis process, high overpotential of an electrocatalytic synthesis reaction, low conversion efficiency, and poor product selectivity. Therefore, it is important to design high-performance electrocatalysts for urea synthesis with an efficient mechanism. In this work, we present a double transition-metal MXene (Mo₂VC₂-MXene) as an excellent candidate with high selectivity for the electrocatalytic synthesis of urea under mild conditions. The key intermediate precursor *CO is unraveled through full reaction energy calculations by taking into account the related reaction pathways. Transition state assessments were also performed for the C–N coupling step and resulted in the targeted kinetic potentials, which are lower potential barriers than that of the Pd–Cu catalyst (0.79 eV). The selectivity performance of the Mo₂VC₂ surface is demonstrated in the electrocatalytic synthesis of urea for the first time. This work consolidates the fundamental theoretical approach for the promising electrocatalytic synthesis of urea. Furthermore, the effort highlights the importance of newly emerged MXenes towards highly efficient electrocatalytic synthesis of urea.