Tuning the Coordination Structure of CuNC Single Atom Catalysts for Simultaneous Electrochemical Reduction of CO2 and NO3– to Urea

Abstract Closing both the carbon and nitrogen loops is a critical venture to support the establishment of the circular, net‐zero carbon economy. Although single atom catalysts (SACs) have gained interest for the electrochemical reduction reactions of both carbon dioxide (CO 2 RR) and nitrate (NO 3 RR), the structure–activity relationship for Cu SAC coordination for these reactions remains unclear and should be explored such that a fundamental understanding is developed. To this end, the role of the Cu coordination structure is investigated in dictating the activity and selectivity for the CO 2 RR and NO 3 RR. In agreement with the density functional theory calculations, it is revealed that Cu‐N 4 sites exhibit higher intrinsic activity toward the CO 2 RR, whilst both Cu‐N 4 and Cu‐N 4− x ‐C x sites are active toward the NO 3 RR. Leveraging these findings, CO 2 RR and NO 3 RR are coupled for the formation of urea on Cu SACs, revealing the importance of *COOH binding as a critical parameter determining the catalytic activity for urea production. To the best of the authors’ knowledge, this is the first report employing SACs for electrochemical urea synthesis from CO 2 RR and NO 3 RR, which achieves a Faradaic efficiency of 28% for urea production with a current density of − 27 mA cm –2 at − 0.9 V versus the reversible hydrogen electrode.