Origin of visible-light-induced photocatalytic properties of S-doped anatase TiO2 by first-principles investigation

Electronic structures and optical absorption spectra of S-doped anatase TiO2 are calculated by means of the first-principles pseudopotential total energy method. Electronic structure analyses demonstrate that isolated S 3p states which appear on the upper edge of the valence band cause the narrowing of the band gap of S-doped TiO2. These changes of electronic structure exert great influence on the optical responses of S-doped TiO2. Our results are in line with recent experimental observations that the redshift of optical absorption could be attributed to these isolated S 3p states on the upper edge of the valence band of S-doped TiO2.