Plasmon‐Assisted Tandem Electrocatalysis for CO ₂ ‐to‐C ₂ H ₅ OH Conversion

Abstract An Ag@AgCu core@satellites electrocatalyst, structured with AgCu alloyed nano‐islands dispersed at metallic Ag core surface, was designed to reveal the plasmon‐assisted tandem electrochemical CO 2 reduction reaction (ECO 2 RR) for selective C 2 H 5 OH production. As unraveled by in situ spectral investigations and theoretical calculations, the core@satellites microstructure enables the tandem ECO 2 RR pathway to happen at the interfaced Ag and AgCu sites to facilitate C 2 H 5 OH formation, with Faradaic efficiency (FE) for C 2 H 5 OH reaching 61.4% at −100 mA cm −2 . Under light, an intensive localized electric field could be excited in the near‐surface region of Ag@AgCu core@satellites, contributing to the increased surface *CO coverage, lowered *COCOH formation barrier and deceased *CHCOH‐to‐C 2 H 5 OH conversion free energy. Thus, a high C 2 H 5 OH selectivity (FE = 65.5%) at industrial‐level current density (−280 mA cm −2 ) was achieved over Ag@AgCu core@satellites in a photo‐electrochemical flow cell.