Capacitive Currents in Redox Switching of Conductive Polymers. Reinterpretation of Polyaniline Electrochemistry

W. MARMISOLLÉ; M. I. FLORIT; D. POSADAS

Niza

Congreso; 61st Annual Meeting of the International Society of Electrochemistry (ISE); 2010

International Society of Electrochemistry (ISE)

It is known that the voltammetric response of conducting polymers (CP) contains a capacitive contribution that is proportional to the amount of oxidized polymer. Despite a large amount of work in this field, only a few works address this problem. The capacitive current is mainly due to the fact that as the polymer is partially oxidized it becomes an electronic conductor with properties similar to a metal and the interphase polymer/solution becomes charged as it is polarized. The presence of the capacitive current distorts the voltammetric response of these conducting polymers and the characteristic peaks parameters, the peak potential and the peak current, do not have their usual meaning. Much of the work on electroactive polymers has been carried out without consideration of this capacitive current contribution and, as we will prove below, all the analysis made without its consideration is necessarily wrong.In this work we show experimental data about the voltammetric response of Pani in acid media that proves that the Feldberg’s model is correct and we extend this model to include the possibility of interaction between the redox centers that allows fitting the experimental data to the model. The fitting of the interaction parameters allows us to reach some conclusions about the energy of interaction between the redox centres in the matrix of the polymer films.