Abstract: Utilizing carbon dioxide and nitrate from industrial wastewater presents a promising and sustainable ap-proach for urea synthesis, which serves as an alternative to conventional high-energy methods. However, the intricate electrochemical urea synthesis process involved multiple intermediates and diverse path-ways, resulting in an unclear reaction mechanism and low efficiency in C-N coupling. In order to address these challenges, we developed a novel Cu-NiNC catalyst featuring both Cu cluster and Ni single atom sites. The Cu-NiNC achieved a urea Faradaic efficiency (FEurea ) of 18.28 %, with a maximum urea yield of 64.24 μg h-1 mg-1 . Through a combination of electrochemical measurements and theoretical calculations, our findings demonstrate that∗NH2 and∗CO intermediates are formed at the Cu and Ni sites, respectively, and subsequently couple to generate the crucial∗CONH2 intermediate, thereby facilitating urea synthe-sis. This study introduces a new perspective on the design of innovative and efficient catalysts for urea synthesis.

Key words: Carbon dioxide, Nitrate, Urea synthesis, Cu-NiNC catalyst, Carbon-nitrogen coupling