Studies on Spontaneous Charging/Discharging Processes of Polypyrrole in Aqueous Electrolyte Solutions

Abstract

Spontaneous processes of polypyrrole (PPy) films in electrolyte solutions resulting from polymer oxidation by dissolved oxygen or polymer redox capacitance discharging and their influence on open circuit potentials were investigated. Chronopotentiometric and chronoamperometric methods were adapted to study these processes. Based on the data obtained and open circuit potential vs. time measurements, Tafel plots, rest (zero-current) potentials and dependences of discharging/charging current on time were determined. Currents resulting from discharge of oxidized polypyrrole are slightly higher for thicker films, while oxidation currents of neutral PPy increase additionally with rising H+ ions and oxygen concentrations. The influence of concentration and kind of electrolyte solution on recorded currents and rest potentials was also taken into consideration. Results of these experiments can be helpful in evaluation of the polymer charge stability. They are also of significance in the explanation of the dependence of open circuit potential of PPy on concentration of solution components, described in the literature, important for analytical applications of conducting polymers.