外在因素对TiO2膜电极/溶液界面CPE行为的影响

电极反应过程本质上是一个界面过程，电极／溶液界面的特性对界面电子转移有决定性的影响，对于同 个电极反应，电极表面性质的不同，界面电子传递的机理就有可能不同，因此，对电极／溶液界面特性进行充分的研究，有助于揭示界面电荷转移的机理，从而有可能有效地按照我们的主观愿望去影响电机反应进行的方向和速度，研究电极／溶液界面最简单的情形是研究所谓的理想极化电极，长期以来，很多学者研究了固体电极／溶液界面的理想极化情况，并将电极／溶液界面的阻抗特性与电极表面的孔隙度、粗糙度、电极表面原子排列不均一性以及溶液的电导等相关联，其中，对电极／溶液界面的恒相位元(CPE,constant phase element）行为－－这个困惑人们多年的问题更是进行了持久、深入、细致的研究。

Effect of Extrinsic Factors on the CPE Behavior of Film TiO2 Electrode

Under ideally polarizable conditions, TiO2 film electrode/solution electrolyte interface exhibited frequency dispersion, The effects of external factors such as the concentration of KNO3, various electrolytes and applied potentials near the flat band potential on the CPE behavior of TiO2 film electrode were studied in electrolyte solution by using A.C. impedance spectra. It was found that concentration of KNO3 had a significant effect on the CPE exponent n only when the concentration is smaller than 0.1 mol· L－ 1. In this concentration range, the CPE exponent n went up with increase of KNO3 concentration, once the concentration was larger than this value, however, the CPE exponent n approached to a constant, irrelevant of the concentration. Near the flat band potential, the influence of applied potential on the exponent n depended on the selected frequency range. When the frequency was in lower range, that is smaller than 0.1 Hz, this influence was obvious,on the other hand, it bore no relation to applied potential in higher frequency. Types of electrolytes only affected the CPE constant Q, having nothing to do with the CPE exponentn.