Mechanistic insights into CN coupling on Zn₁Cu(1 1 1) single-atom alloy for electrocatalytic urea synthesis from CO...

Electrocatalytic urea synthesis provides a promising alternative to conventional energy-intensive industrial processes, yet its progress remains largely limited by the unclear CN coupling mechanism and insufficient catalyst regulation strategies. Using density functional theory calculations, we screened a series of Cu-based single-atom alloys and identified the Zn₁Cu(1 1 1) system as a promising candidate owing to its thermodynamic stability, favorable *CO adsorption behavior, and accessible first CN coupling kinetics. Electronic structure analyses reveal that Zn incorporation promotes its surrounding electron accumulation toward the adjacent Cu sites, thereby optimizing the adsorption of CO/NO-derived intermediates and then facilitating key CN coupling steps. Subsequently, the most favorable reduction pathways were identified by evaluating the stepwise competition among CN coupling, *CO protonation, and the protonation of N-containing intermediates. Compared with pristine Cu(1 1 1), Zn₁Cu(1 1 1) lowers the maximum kinetic barrier from 1.02 eV to 0.85 eV toward urea formation at -0.35 V vs. RHE. More importantly, this study provides atomic-level insight into Cu-based single-atom alloys for electrocatalytic CN coupling and establishes a systematic theoretical workflow for other CN coupling reactions.