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 5 d and 6 s -Au. The electronic properties of the 5 d and 6 s impurity orbitals cause valence widening and band gap narrowing.