Influences of stoichiometry deviations on geometry and electronic structures of TiO2 anatase (101)

We systematically investigated native defects and reconstructions of TiO2 anatase (101) using USPEX and VASP codes. For lightly reduced samples, the coverage of O vacancies at surface depends on its concentration in bulk, while Ti interstitials prefer to dissolve in bulk. Atomic configurations of reconstructed TiO2 anatase (101) structures were given for severe reduced samples at the first time. Increasing the reduction degree, the Fermi level can be modulated in the whole bandgap. For O-rich samples, due to the indirect-to-direct bandgap transition and bandgap narrowing, O interstitials are responsible for visible light photoactivity. In a word, stoichiometry deviations of TiO2 anatase (101) have broad implications for photocatalytic reactions.