X-ray spectroscopic study of the electronic structure of visible-light responsive N-, C- and S-doped TiO2

The electronic origins of the visible-light response of N-, C- and S-doped TiO2 have been studied using X-ray absorption, X-ray emission, and X-ray photoelectron spectroscopies. New electronic states are observed in the bulk band gap, above the valence band edge of pure TiO2, which can be directly related to the visible-light absorption of the N-, C- and S-doped TiO2 materials.