ELECTROCHEMICAL CHARACTERIZATION OF PANI-NAFION MEMBRANES AND THEIR ELECTROCATALYTIC ACTIVITY

PANI-Nafion (R) membranes were prepared by a chemical method in which the faces of a commercial Nafion membrane were contacted with two acid solutions containing an oxidant (Fe3+) and aniline respectively. They were then characterized by a variety of electrochemical techniques (cyclic voltammetry, chronoamperometry, ac impedance). PANI was stored mostly in the vicinity of the Nafion face exposed to the oxidant. When this face was contacted with Hg and the other with electrolyte solutions, typical electrochemical responses of PANI were detected. Electrocatalytic reduction of O2 and oxidation of N2H4 were achieved on PANI-Nafion electrodes and found to be only slightly slowed down with respect to ordinary PANI film electrodes, at variance with a fast process such as Fe3+ reduction, the rate of which was severely limited by diffusion through the membrane.