Exploiting hot electrons from a plasmon nanohybrid system for the photoelectroreduction of CO2

Abstract Plasmonic nanohybrid systems efficiently convert light into electrical charges and heat, enabling their role as mediators in catalytic transformations. While numerous instances of plasmonic photothermal catalytic reactions exist, the participation of hot carriers in these processes remains a subject of vigorous debate. In this study, we present a direct utilization of plasmon hot electrons in the photoelectrocatalytic reduction of CO2 using visible light. Through the deliberate construction of a plasmonic nanohybrid system comprising NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 1,10-Phenanthrolin-5-amine), we demonstrate the immediate involvement of hot electrons in CO2 reduction. Supporting evidence for the engagement of hot electrons in the catalytic process is derived from ultrafast spectroscopy, in situ Fourier-transform infrared spectroscopy (FTIR), electrochemistry, and catalytic testing. Unbiased in situ spectroscopy verified the stepwise reduction of the catalytic system and the generation of CO. This, coupled with the low thermal stability of the ReI(phen-NH2)(CO)3Cl complex, explicitly establishes plasmonic hot carriers as the primary contributors to the process. Mediating catalytic reactions by plasmon hot carriers is feasible and holds promise for further exploration and development in diverse transformations with significant societal impact.