Characterization of Ag-TiO2 Electronic Structures and Nanotubes Based on First-Principles Calculation

Abstract

In this manuscript, we report the simulation of electronic structures of TiO2 doped with Ag using first-principles calculation, based on the density functional theory (DFT) The mechanism to improve the visible-light photocatalytic activity for TiO2 doped with Ag. EF was displaced into the valence band (VB), narrowing the band gap. An independent energy band was also introduced above the VB and an energy band with the width of 0.9 eV is introduced under the conduction band (CB), also resulting in the narrowing of the band gap. New VB and CB were formed by three orbitals O-2p, Ti-3d and Ag-4d. Composite TiO2 nanotubes with Ag-doping were synthesized using the alkaline fusion and hydrothermal method under ambient atmosphere. XRD results indicated composite Ag-TiO2 nanotubes ranging from the single anatase phase to the anatase and rutile mixed phase. XPS showed an increase in the surface acidity and photo catalytic activity of TiO2 nanotubes due to the presence of OH radicals. Furthermore Ag-doping also facilitated the separation of photo-holes and photo-electrons and enhanced the optical properties.