Enhancing C 2 Selectivity in Electrocatalytic CO 2 Reduction Via Synergy of Plasmonic Hot Electrons and Photothermal Effect

Surface plasmon-enhanced electrocatalytic CO₂ reduction offers an attractive dimension beyond conventional electrocatalytic methods by optimizing photon utilization to simplify electrocatalytic reactor designs and enhance reaction activity/selectivity. However, the synergistic regulation mechanism of the complex multiple plasmonic effects on the CO₂ reduction reaction, particularly under electrochemical bias, remains to be thoroughly investigated. This study, based on copper plasmonic electrodes, reveals the key role of localized surface plasmon resonance (LSPR) in enhancing CO₂ conversion and facilitating the transition of the key intermediate *CO from bridge to atop adsorption configuration. Through a combination of experiments and density functional theory calculations, we show that the synergy of plasmonic hot electrons and photothermal effect effectively reduces the C─C coupling energy barrier. Systematic measurements clarify the correlation between the plasmonic excitation of the electrode and the enhanced selectivity of C₂ products. Under optimized conditions, synergetic plasmonic effects significantly promote the CO₂ conversion and enhance the Faradaic efficiency (FE) of C₂ products, with a maximum increase from 57% to 87%. This work not only provides a new perspective for understanding the complex synergistic mechanisms of plasmonic effects, but also opens a new avenue for achieving selective electrocatalytic CO₂ conversion.