Voltammetric study of the influence of cations on the redox-switching process of halogenide-doped polypyrrole

The influence of the nature of cations (K+ and tetraalkylammonium cations TMA(+), TEA(+), TBA(+)) on the electrochemical properties of the chloride- and bromide-doped polypyrrole electrodes in aqueous solutions has been studied. The differences in the shape and evolution of the voltammograms during cycling have been explained by the different participation of the ions in the redox-switching process. The dopant ions have been divided into three groups: free moving, blocked and screened. The charge of the blocked ions is compensated during redox-switching by the insertion of the small cations into the polymer film and the screened ions do not participate in redox process. The ratio of the different forms of dopant ions is dependent on both the properties of the film and solution and can be changed during potential cycling. The structural alteration of the polypyrrole frame during the cycling also affects the ratio of the cation-anion participation in the redox-process. Copyright (C) 1996 Elsevier Science Ltd