Charge transfer processes at poly-o-phenylenediamine and poly-o-aminophenol films

A comparative study of charge transfer at electrodes modified with the title polymer films was performed mainly in I M perchlorate solutions at variable pH by using different electrochemical methods. Experiments with Nafion(R)-coated electrodes were carried out to elucidate the role of the supporting electrolyte anions, also exploiting the results of EQCM measurements. In both films, the charge transport is complicated by background conductance that most likely results from bulk residual charge. Both polymers are doped by hydrogen ions and the effects of supporting electrolyte anions are negligible. The results obtained from low-amplitude measurements showed that the charge transport through both polymer films is accompanied by irreversible injection processes at the film interfaces. A capacity dispersion in the low-frequency range, most likely related to the existence of different states of hydrogen ions in the film, was observed for both polyamines. The problems concerning the treatment of the impedance data obtained for slow injection processes are also discussed. (C) 2004 Elsevier Ltd. All rights reserved.