Effects of oxygen impurities and nitrogen vacancies on the surface properties of the Ta3N5 photocatalyst: a DFT study.

Surface defects and impurities play important roles in the photocatalytic performance of semiconductors. In this study, DFT calculations are performed to investigate the effects of oxygen impurities and nitrogen vacancies on the surface stability and electronic structures of Ta3N5(100), (010) and (001) low-index surfaces. The results show that, for each surface, the oxygen impurities and nitrogen vacancies are beneficial and harmful, respectively, to the surface stability of Ta3N5. The oxygen impurities and nitrogen vacancies have mainly two effects on the surface electronic structures of Ta3N5. One is saturating surface states on the clean surface, and the other is inducing the downshift of conduction band minimum. In addition, the Ta3N5(100) surface with oxygen impurities is expected to have the strongest reduction ability in practice, providing useful guidance for further investigations of Ta3N5 in the photocatalytic hydrogen evolution.