Electronic Structure of Pure and N-Doped TiO2 Nanocrystals by Electrochemical Experiments and First Principles Calculations

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• 作者：Francesca Spadavecchia ; Giuseppe Cappelletti ; Silvia Ardizzone ; Michele Ceotto ; Luigi Falciola
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 14, 2011
• 年：2011
• 卷：115
• 期：14
• 页码：6381-6391
• 全文大小：1181K
• 年卷期：v.115,no.14(April 14, 2011)
• ISSN：1932-7455

文摘

Optical and electrochemical characterizations are carried out in conjunction with first-principles calculations on pure and N-doped titania nanocrystals. These are prepared in laboratory with initial doping concentrations of triethylamine in the range of 0.1鈭?.5 N/Ti molar ratio. Diffuse reflectance UV鈭抳is spectra of N-doped samples present a significant absorption in the visible region. The flatband potential (E_fb) of pure and nitrogen-doped TiO₂ (鈭?.6 卤 0.2 V vs NHE) is determined by impedance spectroscopy (Mott鈭扴chottky plots) and the quasi-Fermi level, ⁿE_F* (鈭?.67虆V vs NHE) by photovoltage measurements as a function of the suspension pH in the presence of an electrochemical probe (methylviologen, MV²⁺). Theoretical density of electronic states calculations, where several N doping versus vacancy combinations are taken into consideration, together with the optical and electrochemical experiments allow us to draw a detailed picture of the electronic features of the doped samples.