CHARGE COMPENSATION DYNAMICS IN THE REDOX PROCESSES OF POLYPYRROLE-MODIFIED ELECTRODES

Electrochemical quartz crystal microbalance (EQCM) data combined with cyclic voltammetry were used to study the ionic exchange process in po lypyrrole films prepared in sulfuric acid solution. A quantitative ana lysis of the results indicates a doping degree of 33% after polymeriza tion and a high polymerization efficiency. Studies performed in monome r-free solutions of Na2SO4, NaNO3, and Cs2SO4 show that both anions an d cations are involved in the charge compensation process. The analysi s of the ionic exchange is made using the integral quantities (charge, mass, number of moles, and molar fraction) and differential quantitie s (ionic fluxes and transport number). The results of such quantitativ e calculations are interpreted taking also into account the transfer o f neutral species like solvent molecules and the physicochemical natur e of the anions and cations involved in the redox process.