阳极氧化制备TiO_2纳米管阵列电极反应及阻抗研究

Electrode Reaction and Impedance Resistance of TiO_2 Nanotube Arrays Prepared by Anodic Oxidation

为使TiO2纳米管阵列电极更好地应用于太阳能电池中,采取恒压阳极氧化法在质量分数0.5%NH4F/甘油电解液中在钛基体上制备出TiO2纳米管阵列。采用XRD、SEM、电子順磁波普仪(EPR)、交流阻抗法(EIS)和循环伏安法(CV)研究TiO2纳米管阵列电极的电子传输性能及界面性质,确定各电极反应过程对应的阻抗曲线,计算得出电极的电子传输动力学参数。研究表明,TiO2纳米管阵列电极表面发生三价钛化合物转化成四价钛氧化物的氧化反应,电极电阻明显降低,加速了电极-电解液界面电子扩散速度,有利于TiO2电极表面自由羟基的产生。

For better application of TiO2 nanotube array electrodes in solar cells, TiO2 nanotube arrays were prepared on a titanium substrate in 0.5wt%NH4F/glycerol electrolyte by means of anodic oxidization at a constant potential. The characteristics of the electron transfer and the interface of the TiO2 nanotube array electrodes were researched by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, electron paramagnetic resonance spectrometer （EPR）, electrochemical impedance spectra （EIS） and cyclic voltammetry （CV）. The impedance curves corresponding to reaction processes of electrodes were determined. Moreover, the dynamic parameters for electron transfer in the electrodes were calculated. The results indicate that the reaction of trivalent titanium compound to tetravalent titanium oxide took place on the surface of the electrodes, leading to great decrease of the resistance of the electrodes. Therefore, the electron pervasion at the electrode-electrolyte interface was accelerated, which was good for the formation of ·OH on the electrode surface