Effects of S/Ce-codoping on electronic structures and optical properties of anatase TiO2 from density functional theory calculations.

The electronic and optical properties of S- and/or Ce-(co)doped anatase titanium dioxide (TiO₂) are investigated using density functional theory plus U (DFTU) calculations. The optimized total energy suggests that TiO₂ codoping by Ce and S favours the configuration of one substitutional Ce atom occupied on a Ti site with one substitutional S atom either on its nearest neighboring O or Ti site. The calculated results show that all doping configurations exhibit remarkable red-shift and excellent photocatalytic properties compared with pure TiO₂. These reinforced features can mainly be ascribed to the appearance of S states in the top of valence band (VB) and Ce states in the bottom of conduction band (CB) as well as the contribution from the increasing octahedral dipole moments. The synergetic effects of cationic Ce and anionic S can extend optical absorption edge, which results in higher absorption coefficient in the visible light region than that of the anionic S monodoping and cationic Ce monodoping case; in the same time, decreasing the codoping concentration leads to reduced optical absorption. Additionally, Ce and S as cations incorporating into TiO₂ lattices can induce stronger redox potential with a lower defect formation energy under O-rich condition compared with other doping systems. [ABSTRACT FROM AUTHOR]