Oxygen vacancies in N doped TiO2: Experiment and first principle calculations

We have determined the electronic and atomic structure of N doped TiO2 using a combination of hard x-ray photoelectron spectroscopy (HAXPES) and first- principles density functional theory calculations. Our results reveal that N doping of TiO2 leads to the formation of oxygen vacancies and the combination of both N impurity and oxygen vacancies accounts for the observed visible light catalytic behavior of N doped TiO2.