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

Selective CO₂ photoreduction to value-added multi-carbon (C₂₊) feedstocks, such as C₂H₄, 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 C₂₊ products with low selectivity. Here we report that through facile surface immobilization of a 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF₄) ionic liquid, plasmonic Cu nanowires could enable highly selective CO₂ photoreduction to C₂H₄ product. At an optimal condition, the resultant plasmonic photocatalyst exhibits C₂H₄ 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-BF₄ 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.