Effects of Valence\nElectron Layer Thickness of Metal\nClusters on Electron–Hole Separation at the Metal/TiO<sub>2</sub> Interface

To elucidate the effects of valence electron layer thickness\nof\nmetal clusters on charge separation in TiO<sub>2</sub> surface, we\nhave conducted nonadiabatic molecular dynamics simulations. Our simulations\ndemonstrate that the valence electron transfer from the conduction\nband of TiO<sub>2</sub> to metal clusters significantly depends on\nthe type of metal clusters. As the thickness of the valence electron\nlayer of metal cluster approaches that of Ti atoms, the valence electrons\nmore easily transfer from the metal cluster to TiO<sub>2</sub>, giving\nrise to a strong built-in electric field. Furthermore, the establishment\nof this built-in electric field intensifies the nonadiabatic (NA)\ncoupling between the metal cluster and TiO<sub>2</sub>, resulting\nin a rapid photogenerated electron transfer from the TiO<sub>2</sub> surface to the metal clusters and efficient charge separation. Thus,\nthe electron transfer times follow the order of Au<sub>13</sub>/TiO<sub>2</sub> > Ag<sub>13</sub>/TiO<sub>2</sub> > Cu<sub>13</sub>/TiO<sub>2</sub>. These results provide critical new insights into\ndeveloping\nhighly efficient photocatalysts by adjusting the valence electron\nlayer thickness of metal clusters to enhance charge separation and\nprolongs charge carrier lifetimes, improving overall catalytic efficiency.