TiO2薄膜光电极能带结构和催化活性的初探

以阳极氧化法制得的TiO2薄膜光电极为工作电极，铂环为对电极，饱和甘汞电极为参比电极，组成光电催化降解苯酚体系．运用电化学阻抗图谱(EIS)，测得光电催化过程中TiO2薄膜光电极的空间电荷层电容，计算出半导体能带结构参数——空间电荷层宽度W．结果证明：当空间电荷层宽度W随阳极偏压增加而增大时，TiO2薄膜电极光催化活性提高；当其等于薄膜厚度时，光催化活性最好，此时出现最佳偏压值；继续增加偏压，活性反而有所下降。

Preliminary Study on Band Structure of TiO2 Thin Photoelectrode and Catalytic Activity

A three-electrode system composed of TiO_2 photoelectrode as the working electrode,Pt ring as the counter electrode and saturated calomel electrode (SCE) as the reference electrode was used for the photoelectrocatalytic degradation of phenol.The TiO_2 thin film photoelectrode was made by anodizing.During the photoelectrocatalytic process,Electrochemical Impedance Spectroscopy (EIS) was applied to measure the capacitance of space charge layer in the TiO_2 semiconductor photoelectrode,and to calculate the band structure parameter-the width W of space charge layer.The results show that photocatalytic activity of TiO_2 electrode is improved when the width broadens with the bias increasing; the activity reaches best when the width is nearly equivalent to the thickness of TiO_2 thin film,then the optimal value of the bias appears; the activity somewhat decreases when the bias is beyond the optimal value.