posted on 2010-02-25, 00:00authored byHonggang Sun, Weiliu Fan, Yanlu Li, Xiufeng Cheng, Pan Li, Xian Zhao
DFT calculations are used to investigate the origin of the experimentally observed changes in the visible photoactivity of cubic and rhombic In2O3 induced by N doping. Two possible mechanisms for the red shift in N-doped In2O3 are tentatively put forward, according to the doping types. For substitutional N-doping models, our results show that, in both polymorphs, partial N 2p states mix with O 2p states and localized lie above the top of the valence band, acting as the frontier orbital level. Electronic transitions from these localized states induce a red shift to the visible region of the optical absorption edge. For interstitial N-doping models, NO π-antibonding states localized in the gap contribute to the impurity levels. The electronic transition from these states may well explain the mechanism of the red shift in interstitial N-doped In2O3. The calculated optical properties for all N-doped In2O3 show a significant visible light absorption at about 400−600 nm, which corresponds to the experimental result. This present work shows that N-doped In2O3 will be a promising photocatalyst with favorable photocatalytic activity in the visible region.