Tailoring Activation Intermediates of CO₂ Initiates C-N Coupling for Highly Selective Urea Electrosynthesis

Electrocatalyzed reduction of CO₂ and NO₃^- to synthesize urea is a highly desirable, but challenging reaction. The bottleneck of this reaction is the C-N coupling of CO₂ and NO₃^- reduction intermediates. In particular, the uncertainty of CO₂ multielectron reduction intermediates severely affects the selectivity and activity of C-N coupling processes involving multiple electron and proton transfers. Here, we present a novel tandem catalyst with two compatible single-atom active sites of Au and Cu on red phosphorus (RP-AuCu) that efficiently converts CO₂ and NO₃^- to urea. Experimental and theoretical prediction results confirmed that the active center of Au on red phosphorus promotes electron transfer between CO₂ molecules and red phosphorus, thereby regulating CO₂ activation intermediates to produce electrophilic *COOH. In addition, the active center of Cu on red phosphorus can enhance the electrophilic attack of *COOH species on *NH₂, thus promoting the selective formation of C-N bonds. Consequently, RP-AuCu exhibited a urea yield of 22.9 mmol g_cat.^-1 h^-1 and a Faraday efficiency of 88.5% (-0.6 V_RHE), representing one of the highest levels of electrocatalytic urea synthesis. This work deepens the understanding of the C-N coupling mechanism and provides an interesting catalyst design approach for the efficient and sustainable production of C-N compounds.