Ac-electrogravimetry study of ionic exchanges on a polypyrrole modified electrode in various electrolytes

For many years, polypyrrole films have appeared to be the most studied conducting polymer. Unfortunately, shadows still remain concerning the electrochemical mechanisms of these films and in particular, the aspect which concerns the limiting step which governs the electrochemical response. Different possibilities are available such as the transport of ionic species in the film, the electron transfer at the electrode/film or the electron motion in the film, the ionic exchanges at the film/interface electrolyte. Classical electrochemical methods do not permit to discriminate between these effects. Ac-electrogravimetry technique was used here to demonstrate that the electrochemical behaviour of thin pPy films is governed by the ionic insertion without any doubt. Particular parameters were modified as the ionic atomic weight or the electrolyte concentration to corroborate this idea.