Enhancing CO₂ Electroreduction to Ethylene via Copper−Silver Tandem Catalyst in Boron‐Imidazolate Framework Nanosheet

Abstract Copper‐based tandem catalysts with a well‐defined Cu coordination environment for the electrochemical CO₂ reduction reaction (CO₂RR) are highly desirable, due to their unique geometric‐electronic properties and helpfulness for revealing structure–property correlations. Here, this work synthesizes a tandem catalyst at atomic configuration scale, Ag@BIF‐104NSs(Cu), by using the ultrathin boron imidazolate framework (BIF) nanosheets as support to load Ag nanoparticles (NPs). Due to the highly ordered benzoate ligands decorated on the Cu sites of BIF‐104NSs(Cu), Ag NPs are located in atomic proximity to Cu sites via a coordination effect. Electrochemical CO₂RR measurements show this tandem catalyst highly improves the selectivity and activity for the CO₂ reduction to ethylene. The faradaic efficiency (FE_C2H4) of 21.43% is significantly higher than that of BIF‐104NSs(Cu) (3.82%). Further, density functional theory calculations reveal that the Ag sites in the composite can efficiently reduce CO₂ to *CO, that subsequently migrate to the Cu sites. Thereafter, the Cu–Ag atom pair is responsible for the C–C coupling of the local enriched *CO and further formation of C₂H₄.