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

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 (FEC2H4) 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.