Activity-Selectivity Trends in Electrochemical Urea Synthesis: Co-Reduction of CO2 and Nitrates Over Single-Site Catalysts.

Electrochemical co-reduction of carbon dioxide and nitrates (CO2NO3RR) holds promise for sustainable urea production. However, the sluggish kinetics of the sixteen-electron transfer and unclear mechanistic understanding strongly impede its development. Here, combined experimental and computational approaches are employed to screen a series of metal phthalocyanine as model catalysts (MPcs, M = Zn, Co, Ni, Cu, and Fe) to uncover the activity-selectivity trends in electrochemical CO2NO3RR. The theoretical simulations reveal that the thermodynamics of urea synthesis is significantly influenced by key intermediates, where the enhanced adsorption of *HOOCNO, coupled with reduced adsorptions of *N and *COOH, and moderate adsorption of *H2O, can significantly promote the urea production. ΔG*HOOCNO-ΔG*N-ΔG*COOH+ΔG*H2O as a potential descriptor is proposed for predicting the efficiency of CO2NO3RR toward urea formation. The findings provide systematic guidance for the future design of high-efficiency catalysts for urea electrosynthesis, addressing a crucial need for sustainable nitrogen fixation.