DFT Investigations of Au(n) Nano-Clusters Supported on TiO(2) Nanotubes: Structures and Electronic Properties

TiO(2) nanotubes (TiO(2)NTs) are beneficial for photogenerated electron separation in photocatalysis. In order to improve the utilization rate of TiO(2)NTs in the visible light region, an effective method is to use Au(n) cluster deposition-modified TiO(2)NTs. It is of great significance to investigate the mechanism of Au(n) clusters supported on TiO(2)NTs to strengthen its visible-light response. In this work, the structures, electronic properties, Mulliken atomic charge, density of states, band structure, and deformation density of Au(n) (n = 1, 8, 13) clusters supported on TiO(2)NTs were investigated by DMOL3. Based on published research results, the most stable adsorption configurations of Au(n) (n = 1, 8, 13) clusters supported with TiO(2)NTs were obtained. The adsorption energy increased as the number of Au adatoms increased linearly. The Au(n) clusters supported on TiO(2)NTs carry a negative charge. The band gaps of the three most stable structures of each adsorption system decreased compared to TiO(2)NTs; the valence top and the conduction bottom of the Fermi level come mainly from the contribution of 5d and 6s-Au. The electronic properties of the 5d and 6s impurity orbitals cause valence widening and band gap narrowing.