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

The electrochemical reduction of CO₂ to C₂H₄ offers a sustainable pathway to mitigate CO₂ emissions and produce valuable chemicals. However, developing stable electrocatalysts with high activity and C₂H₄ 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 C₂H₄ 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 CO₂, (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 CO₂ toward the formation of C₂H₄. This study provides new insight into designing efficient tandem catalysts with *CO/Cu(I)-enriched local microenvironment for superior multicarbon electrosynthesis from CO₂RR.