DFT-Based Theoretical Calculations of Nb- and W-Doped Anatase TiO2: Complex Formation between W Dopants and Oxygen Vacancies

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• 作者：Hideyuki Kamisaka ; Takahiro Suenaga ; Hisao Nakamura ; Koichi Yamashita
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：July 29, 2010
• 年：2010
• 卷：114
• 期：29
• 页码：12777-12783
• 全文大小：363K
• 年卷期：v.114,no.29(July 29, 2010)
• ISSN：1932-7455

文摘

The structure and electronic states in Nb-doped TiO₂ (TNO) and W-doped TiO₂ (TWO) having the anatase phase were investigated using a first-principles DFT-based band structure method. In addition to the cases where the dopant substituted for a Ti atom, cells containing a dopant (M_Ti, where M = Nb and W) and an oxygen vacancy (V_O) were calculated to clarify the role of oxygen vacancies in the system. Furthermore, cells containing two dopants and an oxygen vacancy (2M_Ti−V_O) and cells with a dopant and two oxygen vacancies (M_Ti−2V_O) were calculated. Energetically stable structures were found in the 2W_Ti−V_O and W_Ti−2V_O cells sampled, whereas the corresponding structures in TNO did not show any significant energy stabilization. Impurity states were found in the stable 2W_Ti−V_O and W_Ti−2V_O structures, and an approach of the two W_Ti atoms was found in 2W_Ti−V_O. These findings suggest the possible formation of complex structures consisting of W_Ti dopants and oxygen vacancies. Our results are consistent with recent experiments on TWO by Takeuchi et al., and they rationalize the lower electronic conductivity of TWO versus TNO.