ADSORPTION AND OXIDATION OF THIOPHENE-3-METHANOL ON PLATINUM-ELECTRODES STUDIED BY ELECTROCHEMICAL AND IR SPECTROSCOPIC METHODS

The adsorption and oxidation of thiophene-3-methanol on platinum have been studied by in situ IR spectroscopy, and by using the ferrocene/fe rrocinium redox couple as a probe of the state of the electrode surfac e. In addition, ex situ IR spectra were recorded from bulk poly(thioph ene-3-methanol) (PTM) films. The results show that an adsorbed layer o f mainly PTM is formed on platinum at potentials lower than the beginn ing of the voltammetric oxidation peak of the monomer. The IR spectra indicate that the molecular structure of this layer and that of the el ectrosynthesized bulk PTM are quite similar. Both were found to contai n C-O-C coupled monomer units. The features due to C-O-C bonding were weaker in the IR spectra obtained from PTM bulk films synthesized ex s itu with high current densities than in the in situ spectra recorded i n a thin layer cell in which the use of high current densities is not possible. The results confirm our previously presented hypotheses of a n adsorptive type of formation of PTM, and of a polymerization includi ng two competing coupling paths, namely C-C and C-O-C.