Analysis of Indium Oxidation State on the Electronic Structure and Optical Properties of TiO(2)

Due to the high formation energy of Indium interstitial defect in the TiO(2) lattice, the most probable location for Indium dopant is substitutional sites. Replacing Ti by In atom in the anatase TiO(2) shifted the absorption edge of TiO(2) towards visible regime. Indium doping tuned the band structure of TiO(2) via creating In 5p states. The In 5p states are successfully coupled with the O 2p states reducing the band gap. Increasing In doping level in TiO(2) improved the visible light absorption. Compensating the charge imbalance by oxygen vacancy provided compensated Indium doped TiO(2) model. The creation of oxygen vacancy widened the band gap, blue shifted the absorption edge of TiO(2) and declined the UV light absorption. The 2.08% In in TiO(2) is the optimal Indium doping concentration, providing suitable band structure for the photoelectrochemical applications and stable geometrical configuration among the simulated models. Our results provide a reasonable explanation for the improved photoactivity of Indium doped TiO(2).