Theoretical Insights into Excitation-Induced Oxygen Activation on a Tetrahedral Ag₈ Cluster

Research on small-molecule dissociation on plasmonic silver nanoparticles is on the rise. Herein, we investigate the effect of various parameters of light, i.e., field strength, polarization direction, and energy of oscillation, on the dynamics of oxygen upon photoexcitation of the O₂@Ag₈ composite using real-time time-dependent density functional theory calculations with Ehrenfest dynamics. From our excited-state dynamics calculations, we found that increasing the strength of the external electric field brings a significant contribution to the O-O dissociation. In addition, the polarization direction of the incident light becomes important, especially at weaker field strengths. The light that is polarized along the direction of charge transfer from the metal to adsorbate and the light that is polarized along the long axis of molecular oxygen were found to enhance the bond breaking of O₂ significantly. We also found that at the weakest electric field strength, the oxygen molecule stays adsorbed to the silver cluster when the incident light resonates with low-energy excited states and desorbs away from the metal cluster with high-energy excitations. With strong electric fields, oxygen either desorbs or dissociates.