TY - JOUR
T1 - Localized Excitation of Ti3+ Ions in the Photoabsorption and Photocatalytic Activity of Reduced Rutile TiO2
AU - Wang, Zhiqiang
AU - Wen, Bo
AU - Hao, Qunqing
AU - Liu, Li Min
AU - Zhou, Chuanyao
AU - Mao, Xinchun
AU - Lang, Xiufeng
AU - Yin, Wen Jin
AU - Dai, Dongxu
AU - Selloni, Annabella
AU - Yang, Xueming
PY - 2015/7/22
Y1 - 2015/7/22
N2 - In reduced TiO2, electronic transitions originating from the Ti3+-induced states in the band gap are known to contribute to the photoabsorption, being in fact responsible for the material's blue color, but the excited states accessed by these transitions have not been characterized in detail. In this work we investigate the excited state electronic structure of the prototypical rutile TiO2(110) surface using two-photon photoemission spectroscopy (2PPE) and density functional theory (DFT) calculations. Using 2PPE, an excited resonant state derived from Ti3+ species is identified at 2.5 ± 0.2 eV above the Fermi level (EF) on both the reduced and hydroxylated surfaces. DFT calculations reveal that this excited state is closely related to the gap state at ∼1.0 eV below EF, as they both result from the Jahn-Teller induced splitting of the 3d orbitals of Ti3+ ions in reduced TiO2. Localized excitation of Ti3+ ions via 3d → 3d transitions from the gap state to this empty resonant state significantly increases the TiO2 photoabsorption and extends the absorbance to the visible region, consistent with the observed enhancement of the visible light induced photocatalytic activity of TiO2 through Ti3+ self-doping. Our work reveals the physical origin of the Ti3+ related photoabsorption and visible light photocatalytic activity in prototypical TiO2 and also paves the way for the investigation of the electronic structure and photoabsorption of other metal oxides. (Figure Presented).
AB - In reduced TiO2, electronic transitions originating from the Ti3+-induced states in the band gap are known to contribute to the photoabsorption, being in fact responsible for the material's blue color, but the excited states accessed by these transitions have not been characterized in detail. In this work we investigate the excited state electronic structure of the prototypical rutile TiO2(110) surface using two-photon photoemission spectroscopy (2PPE) and density functional theory (DFT) calculations. Using 2PPE, an excited resonant state derived from Ti3+ species is identified at 2.5 ± 0.2 eV above the Fermi level (EF) on both the reduced and hydroxylated surfaces. DFT calculations reveal that this excited state is closely related to the gap state at ∼1.0 eV below EF, as they both result from the Jahn-Teller induced splitting of the 3d orbitals of Ti3+ ions in reduced TiO2. Localized excitation of Ti3+ ions via 3d → 3d transitions from the gap state to this empty resonant state significantly increases the TiO2 photoabsorption and extends the absorbance to the visible region, consistent with the observed enhancement of the visible light induced photocatalytic activity of TiO2 through Ti3+ self-doping. Our work reveals the physical origin of the Ti3+ related photoabsorption and visible light photocatalytic activity in prototypical TiO2 and also paves the way for the investigation of the electronic structure and photoabsorption of other metal oxides. (Figure Presented).
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U2 - 10.1021/jacs.5b04483
DO - 10.1021/jacs.5b04483
M3 - Article
C2 - 26121118
AN - SCOPUS:84937801912
VL - 137
SP - 9146
EP - 9152
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 28
ER -