Defect-Induced Triple Synergistic Modulation of CuBi Clusters for Enhanced Urea Electrosynthesis

Electrochemical C-N coupling of CO₂ and NO₃ ^- is a promising green approach for synthesizing urea. However, achieving efficient C-N coupling remains challenging because of the kinetic mismatch between CO₂ and NO₃ ^- reduction. Stabilizing key N-containing intermediates to facilitate their coupling with C-containing intermediates is crucial for achieving high Faradaic efficiency. In this study, defect-rich CuBi clusters (D-CuBi) were synthesized, and the effects of the enhanced functionalities of the defects of D-CuBi on the performance of urea synthesis at different critical processes were systematically investigated. Density functional theory calculations and in situ electrochemical spectroscopic analysis revealed that the defects in D-CuBi facilitated the adsorption of CO₂ and prevented the desorption of the key *NO₂ intermediate as NO₂ ^-. Moreover, these sites facilitated the adsorption of active water molecules, thereby accelerating the reaction kinetics for urea production. As a result, the D-CuBi catalyst achieved a remarkable urea Faradaic efficiency of 53.1% and a yield rate of 2.57 µmol h^-1 cm^-2 at -1.0 V vs. the reversible hydrogen electrode, representing an approximately tenfold enhancement over the intact CuBi. This work presents insight into urea electrosynthesis from CO₂ and NO₃ ^- through defect engineering.