Abstract: 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.

Key words: Polyaniline, TiO₂, Photoelectrochemistry