Electronic Structure of F-Doped Bulk Rutile, Anatase, and Brookite Polymorphs of TiO2

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• 作者：Sergio Tosoni ; Oriol Lamiel-Garcia ; Daniel Fernandez Hevia ; Jos茅 Miguel Do帽a ; Francesc Illas
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：June 14, 2012
• 年：2012
• 卷：116
• 期：23
• 页码：12738-12746
• 全文大小：495K
• 年卷期：v.116,no.23(June 14, 2012)
• ISSN：1932-7455

文摘

This work investigates the atomic and electronic structure of fluorine-doped (F-doped) rutile, anatase, and brookite polymorphs of TiO₂. In a first step, we present a methodological analysis of the performance of several density functional schemes (GGA, GGA+U, and hybrid functionals) in reproducing experimental structures and band gap of rutile and anatase. The PBE+U functional appears to provide the best choice, and it is the one chosen to study suitable supercell models of F-doped bulk rutile, anatase, and brookite. We find that F-doping is thermodynamically stable for all polymorphs. In anatase, the Ti³⁺ gap states arising from doping are well located in the middle of the band gap which is convenient for photocatalysis purposes. However, in the case of rutile and brookite, F-doping does not lead to a remarkable reduction of the band gap. We present also results concerning F-doping on reduced titania and provide evidence that the presence of oxygen vacancies does not change significantly the electronic properties of F-substituted TiO₂, albeit slightly stabilizing the resulting system.