Plasmon-Mediated CO₂ Photoreduction via Indirect Charge Transfer on Small Silver Nanoclusters

Due to its relatively high inertness and presence as a key component of the greenhouse gases, CO 2 reduction is highly significant from both scientific and socioeconomic points of view but is very challenging. Plasmon-induced photoreduction of CO 2 offers a potentially effective route to stimulate CO 2 conversion. However, the dynamics of photoinduced charge carriers and the associated microscopic mechanism remain elusive. Here we investigate the ultrafast carrier dynamics of plasmon-mediated photoreduction of CO 2 on prototypical plasmonic silver nanoclusters represented by Ag 6, Ag 20, and Ag 147 using real-time time-dependent density functional theory at the femtosecond scale and single-molecule level. It is found that the CO 2 molecule adsorbed on the tip of these clusters can be efficiently split into a CO molecule and an O atom within 200 fs upon laser illumination, with the cleavage of the C═O bond becoming more readily with the increasing size of the nanoparticles. Our results demonstrate that indirect charge transfer driven by the localized surface plasmon on these small silver nanoparticles dominates the reduction process of CO 2 . The present findings provide explicit pathways for CO 2 photoreduction and offer new insights in designing highly efficient plasmon-mediated photocatalysts.