Au/PATP/PANI膜电极和Au/PATP/PANI/TiO2膜电极的光电化学

聚苯胺（PANI）是一种结构、 性质不同于聚乙炔和聚吡咯的新型导电高聚物,有着十分广泛的应用[1,2].近年来利用光电化学研究聚苯胺的电子结构、 掺杂情况引起人们的重视[3～5].在酸性溶液中电聚合制备聚苯胺的循环伏安曲线上出现两对氧化还原峰,其峰值电位分别为E11/2=0.13 V和E21/2=0.7 V(对饱和甘汞电极).通过改变电极电位,可获得部分氧化态、还原态、氧化态等3种状态的聚苯胺.部分氧化态具有金属导电性,还原态和氧化态均为绝缘体.本文测量3种状态聚苯胺膜电极的光电响应,首次得到其光电流谱,发现聚苯胺一些新的光电化学实验结果.提出了覆盖绝缘体的金属内发射的光电化学模型.同时,在聚苯胺膜上电沉积纳米TiO2微粒膜,得到广谱区的复合光电材料.

The Photoelectrochemistry of Au/PATP/PANI Film Electrode and Au/PATP/PANI/TiO2 Film Electrode

Au/PATP/PANI (polyaniline) film electrode was prepared by voltamometry in_0.5mol/Laniline/0.5 mol/L HClO₄from -0.2-0.8 Vat 100 mV/s after selfassembling PATP(4aminothiophenol) on bare Au. The potential dependence of photocurrent and the photocurrent spectra of Au/PATP/PANIfilm electrode were obtained. The potential dependence of photocurrent showed that all of the three forms(oxidized/partiallyoxidized/reduced) of PANIfilm had both anodic photocurrent and cathodic photocurrent. The halfoxidized PANIfilm had a great photoelectrochemical response. The photocurrent spectra of Au/PATP/PANIfilm electrode showed both half oxidized and reduced PANIfilm had the characteristics of subbandgap photocurrent spectra and followed Fowler rule(IPCE^1/2 =E_threshold+ bhν). Aphotoelectrochemical model on internal photoemission at insulator covered metal was presented to interpret it, which agreed with the model of granular metal island. The model assumed metallic polymer particles embedded in the nonmetallic matrix, while, Au/PATP/PANI/TiO₂film electrode was prepared by electrodeposition in TiCl₃solution (pH≈2.2). The photocurrent spectra of Au/PATP/PANI/TiO₂film possessed the photoelectrochemical characteristics of both TiO₂and PANI. The Au/PATP/PANI/TiO₂film was expected to improve the efficient absorption of solar light.