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

摘要

The adsorption and oxidation of thiophene-3-methanol on platinum have been studied by in situ IR spectroscopy, and by using the ferrocene/ferrocinium redox couple as a probe of the state of the electrode surface. In addition, ex situ IR spectra were recorded from bulk poly(thiophene-3-methanol) (PTM) films. The results show that an adsorbed layer of mainly PTM is formed on platinum at potentials lower than the beginning of the voltammetric oxidation peak of the monomer. The IR spectra indicate that the molecular structure of this layer and that of the electrosynthesized bulk PTM are quite similar. Both were found to contain 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 situ with high current densities than in the in situ spectra recorded in a thin layer cell in which the use of high current densities is not possible. The results confirm our previously presented hypotheses of an adsorptive type of formation of PTM, and of a polymerization including two competing coupling paths, namely C-C and C-O-C. [References: 15]