Building a *CO/Cu(I)-Enriched Local Microenvironment for Enhanced CO ₂ Electroreduction with Superior Ethylene Selectivity

The electrochemical reduction of CO 2 to C 2 H 4 offers a sustainable pathway to mitigate CO 2 emissions and produce valuable chemicals. However, developing stable electrocatalysts with high activity and C 2 H 4 selectivity remains challenging. Herein, a tandem nanocatalyst, Ni 5wt% Cu(TA) 2, featuring closely adjacent Ni and Cu catalytic sites, has been identified as an exceptional and stable catalyst achieving a remarkable C 2 H 4 Faradaic efficiency (FE) of 70.07% at a high current density of 211.43 mA cm –2 . In situ surface characterizations combined with theoretical calculations revealed that introducing Ni into the Cu(TA) 2 structure fulfilled three essential functions: (1) ensuring a steady *CO supply by efficiently converting CO 2, (2) facilitating *CO migration from Ni to adjacent Cu sites to establish a locally *CO-rich microenvironment, and (3) modulating the surface electronic structure to improve the ratio of Cu(I) active centers that favor C–C coupling. These synergistic effects promote the reduction of CO 2 toward the formation of C 2 H 4 . This study provides new insight into designing efficient tandem catalysts with *CO/Cu(I)-enriched local microenvironment for superior multicarbon electrosynthesis from CO 2 RR.