Plasmon‐Driven Highly Selective CO2 Photoreduction to C2H4 on Ionic Liquid‐Mediated Copper Nanowires

Selective CO 2 photoreduction to value‐added multi‐carbon (C 2+ ) feedstocks, such as C 2 H 4 , holds great promise in direct solar‐to‐chemical conversion for a carbon‐neutral future. Nevertheless, the performance is largely inhibited by the high energy barrier of C−C coupling process, thereby leading to C 2+ products with low selectivity. Here we report that through facile surface immobilization of a 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIM‐BF 4 ) ionic liquid, plasmonic Cu nanowires could enable highly selective CO 2 photoreduction to C 2 H 4 product. At an optimal condition, the resultant plasmonic photocatalyst exhibits C 2 H 4 production with selectivity up to 96.7 % under 450 nm monochromatic light irradiation, greatly surpassing its pristine Cu counterpart. Combined in situ spectroscopies and computational calculations unravel that the addition of EMIM‐BF 4 ionic liquid modulates the local electronic structure of Cu, resulting in its enhanced adsorption strength of *CO intermediate and significantly reduced energy barrier of C−C coupling process. This work paves new path for Cu surface plasmons in selective artificial photosynthesis to targeted products.