钛表面二氧化钛膜中氧空位点缺陷传输性能的电化学研究

"钛/TiO2氧化膜/溶液"界面电极体系的电化学性能主要决定于钛表面的TiO2氧化物膜.本文利用多种电化学技术,结合半导体物理的Mott-Schottky分析和Einstein方程,研究了金属钛在1.0mol·L-1HClO4溶液中表面半导体TiO2氧化膜的生长及氧化膜中氧空位点缺陷在外加电场作用下的传输性能,并根据离子性电荷传输与电子性电荷传输对电场变化响应时间之不同特点,确定氧化膜中点缺陷扩散系数.结果表明,电极电位或阳极析氧反应对稳态电流(iss)、氧化膜的阳极化常数(α)、膜中电场强度()、以及膜中氧空位点缺陷的扩散系数(D0)等重要物理化学参数,均有显著影响,并依据氧化膜中的结构变化进行分析.

Electrochemical Studies on the Ionic Charge Transfer Properties of the Oxygen Vacancy Defects in the Oxide Films Formed on Titanium

The ionic charge transfer properties of the oxygen vacancy point defects in TiO2 films formed on titanium were studied in 1.0 mol·L-1 HClO4 solution with cyclic voltammetry,potentiostatic polarization,galvanostatic reduction and capacitance measurements. The measured capacitance data were analyzed based on the Mott-Schottky equation and Einstein equation. Based on the different response times to the changes of the applied electric field between the ionic and the electronic charge transfers,the diffusion coefficient of the point defects in the anodic oxide film on titanium was estimated. It was shown that the passive potential region for titanium in 1.0 mol·L-1 HClO4 ranged from ca. 0 to 6 V. Some important physico-chemical properties in relation with the point defects (oxygen vacancy) transfer,such as the steady-state current (iss),the film oxidization factor (α),the field strength within the film () and the diffusion coefficient of the oxygen vacancies (DO),were found to be potential-dependent. The effects of anodic oxygen evolution and of the film structure changes at higher potentials on the film bulk properties were also discussed.