Interatomic electron transfer promotes electroreduction CO₂-to-CO efficiency over a CuZn diatomic site

Diatomic site catalysts (DACs) with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts (SACs). Herein, we have designed a CuZn diatomic site (CuZn-DAS) electrocatalyst with unique coordination structure (CuN₄–ZnN₄) by anchoring and ordering the spatial distance between the metal precursors on the carbon nitride (C₃N₄) derived N-doped carbon (NC) substrate. The CuZn-DAS/NC shows high activity and selectivity for electroreduction CO₂ into CO. The Faradaic efficiency for CO of CuZn-DAS/NC (98.4%) is higher than that of Cu single atomic site on NC (Cu-SAS/NC) (36.4%) and Zn single atomic site on NC (Zn-SAS/NC) (66.8%) at −0.6 V versus reversible hydrogen electrode (vs. RHE). In situ characterizations reveal that the CuZn-DAS is more favorable for the formation and adsorption of *COOH than those of the electrocatalysts with single atomic site. Theorical calculations show that the charge redistribution of Zn site in CuZn-DAS/NC caused by the considerable electron transfers from Zn atoms to the adjacent Cu atoms can reduce the adsorption energy barriers for *COOH and *CO production, improving the activity and CO selectivity.