Efficient Electrocatalytic Urea Formation from Gas Pollutants on Heteronuclear Dual-Metal Atom Anchored N-Doped Graphene

The electrochemical synthesis of urea under mild conditions is considered a promising alternative to the harsh industrial Haber-Bosch process. However, the development of highly active and selective electrocatalysts remains a formidable challenge. In this study, a novel mechanism for urea synthesis on dual-atom catalysts (DACs) using two gas pollutants (NO and CO) is proposed based on density functional theory (DFT) calculations. It is found that urea can be synthesized through consecutive C-N coupling and hydrogenation steps on heteronuclear DACs, in which the stable adsorption of NO and CO on DACs significantly contributes to the excellent performance for urea formation. Notably, only CoZn, CoCu, and FeZn@N-6/C can continuously accept proton-electron and ultimately achieve urea formation, exhibiting low limiting potentials of -0.27, -0.30, and -0.60 V, respectively. Furthermore, it is also determined that an alternative mechanism is preferable on three DACs. Moreover, competitive hydrogen evolution reaction, as well as reductions of CO and NO reductions, can be effectively suppressed, thereby endowing high selectivity for urea generation. Importantly, this study not only advances a novel mechanism for urea production utilizing gas pollutants but also broadens the applicability of DACs in electrocatalysis.