Electrical and Point Defect Properties of TiO2 Nanotubes Fabricated by Electrochemical Anodization

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• 作者：Ilie Hanzu ; Thierry Djenizian ; Philippe Knauth
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：April 7, 2011
• 年：2011
• 卷：115
• 期：13
• 页码：5989-5996
• 全文大小：1028K
• 年卷期：v.115,no.13(April 7, 2011)
• ISSN：1932-7455

文摘

Pure and N-doped titanium oxide nanotubes (TiO₂nt) were manufactured by anodization of sputtered Ti thin films on a Si (100) substrate. Both solid state contacts and electrolyte contacts were used to investigate the properties of TiO₂nt. Mott鈭扴chottky analysis gave a flat-band potential E_fb = 鈭?.57 V vs Ag/AgCl for pure TiO₂nt and E_fb = 鈭?.22 V vs Ag/AgCl for N-doped TiO₂nt. The charge carrier density was N_D = 6.7 脳 10²⁰ cm^鈭? for pure TiO₂nt and N_D = 3.9 脳 10²⁰ for N-doped TiO₂nt. This corresponds to 1.1% oxide ion vacancies in pure TiO₂nt. In nitrogen-doped TiO₂nt, the decrease of donor density would correspond to 0.47% of vacancies being occupied by nitrogen acceptors. This investigation also allowed estimation of the apparent diffusion coefficient of H⁺ in TiO₂nt. Following the Randles鈭扴evcik method, the effective proton diffusion coefficient in TiO₂nt is (2 卤 1)路10^鈭?1 cm² s^鈭? while in N-doped TiO₂nt it is (4 卤 1)路10^鈭?1 cm² s^鈭?. Using the Warburg diffusion element determined by electrochemical impedance spectroscopy, the proton diffusion coefficient is (2 卤 1)路10^鈭?1 cm² s^鈭? for pure TiO₂nt while for nitrogen-doped TiO₂nt a value of (7 卤 3)路10^鈭?1 cm² s^鈭? is found. These values are consistent with those of the Randles鈭扴evcik method.