Abstract
Semiconductor photocatalysts that can produce hydrogen from water splitting are of great interest. Among the various possibilities, nitrogen (N)-doped is a promising candidate for hydrogen evolution under visible-light irradiation. In this study, hybrid density-functional calculations are employed to investigate the stability and impact of nitrogen impurities on the electronic and optical properties in . We find that the substitutional N on O site () is a deep acceptor in . Moreover, predominates over other N-related defects under equilibrium growth conditions in -type . Our results reveal that gives rise to visible-light absorption in agreement with experimental observations. In addition, we find that hydrogen can bind to , forming complex which leads to a blueshift in the optical absorption. Other N configurations can also contribute to optical absorption in the visible range. The vibration frequencies of different N configurations are provided to support identification using vibrational spectroscopy techniques.
- Received 5 December 2016
- Revised 17 March 2017
DOI:https://doi.org/10.1103/PhysRevB.95.205204
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