Voltammetric Studies of Electrodes in Contact with Ionomeric Membranes

Cyclic voltammetry studies were carried out on platinum and gold screen electrodes in contact with Nafion ionomeric membranes. In addition, experiments were carried out on multiple combinations of platinum screens with either graphite felt or gold screen electrodes, with only one of the electrodes in direct contact with th membrane. In the case of platinum and gold screens, it was found that the voltammograms were almost identical to that found for the same screens in acidic aqueous electrolytes. When two platinum screens were used, the adsorption charge on the platinum doubled. Obviously, adsorption can occur on sites remote from the membrane/electrode contact, provided the metal is wetted with water. In the case of platinum, a mechanism based on rapid mobility of absorbed hydrogen and hydroxyl species is proposed. The implications of these findings regarding solid polymer electrolyte electrolyzers and fuel cells are discussed.