Aminotriazole-Modified Cu Promotes *CO–*COH Coupling via Dual- Active-Site Synergy for Efficient Ethylene Production

Electrochemical CO2 reduction (ECR) on Cu-based catalysts suffers from limited C2H4 selectivity due to competing reaction pathways involving multiple intermediates. Enhancing the selectivity hinges on promoting the formation of *OCCOH, the key intermediate for C2H4 that arises from the coupling of *CO and *COH. Since 3,5-diamino-1,2,4-triazole (Datz) itself can activate CO2 to generate *COH, its integration with Cu offers a promising strategy to promote *OCCOH formation and enhance C2H4 selectivity. To realize this dual-active-site synergy, in this work, we engineered three distinct architectures including Datz-mixed Cu (Cu+Datz), Datz-coordinated Cu (Cu-Datz), and Datz-modified Cu (Cu@Datz) to identify the optimal architecture for realizing *CO–*COH coupling. Among them, Cu@Datz achieves a C2H4 Faradaic efficiency of ~73% at 600 mA·cm-2 and partial current density of 455.3 mA·cm-2. Combined structural characterization, performance analysis and in-situ synchrotron radiation infrared (SR-IR) spectroscopy confirms Datz and Cu dual-sites active synergistically to form *OCCOH, enabling highly efficient C2H4 production.