FREESTANDING MEMBRANES FOR THE STUDY OF ELECTROCHEMICAL REACTIONS OCCURRING AT CONDUCTING POLYMER ELECTROLYTE INTERFACES/

A double submerged impinging jet (DSIJ) cell has been built allowing a n identical hydrodynamic regime to be established on both faces of a b ipolar electrode consisting of either a Pt sheet or a free-standing po lypyrrole (PPy) membrane. Both electrode materials have been studied i n this cell, in the presence of electrolytes containing redox couples. The experimental current-potential characteristics and impedance diag rams relative to PPy may be analyzed as the result of two parallel pat hs of charge transport involving (i) convective diffusion of the redox species in solution, electron transfer at the polymer/electrolyte int erface, and electron transport within the film and (ii) migration of n onelectroactive ions in solution, ion transfer at the polymer/electrol yte interface, and ion transport within the film. In the most favorabl e circumstance of a ast redox couple and a low ionic conductivity of t he membrane, comparison between Pt and PPy explicitly shows an electro catalytic effect of the latter.