Band gap narrowing of titanium dioxide by sulfur doping

Abstract

Titanium dioxide ( TiO 2 ) doped with sulfur (S) was synthesized by oxidationannealing of titanium disulfide ( TiS 2 ). According to the x-ray diffraction patterns, TiS 2 turned into anatase TiO 2 when annealed at 600 ° C . The residual S atoms occupied O-atom sites in TiO 2 to form Ti – S bonds. The S doping caused the absorption edge of TiO 2 to be shifted into the lower-energy region. Based on the theoretical analyses using ab initio band calculations, mixing of the S 3p states with the valence band was found to contribute to the band gap narrowing.