Effects of S/Ce-codoping on electronic structures and optical properties of anatase TiO2from density functional theory calculations

Abstract

The electronic and optical properties of S- and/or Ce-(co)doped anatase titanium dioxide (TiO2) are investigated using density functional theory plus U (DFT[Formula: see text]U) calculations. The optimized total energy suggests that TiO2codoping 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 [Formula: see text] states in the top of valence band (VB) and Ce [Formula: see text] 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 TiO2lattices can induce stronger redox potential with a lower defect formation energy under O-rich condition compared with other doping systems.