The characteristics of a gas diffusion hybrid polymer electrode in the oxygen reduction reaction

Abstract

A new type of gas diffusion electrode has been prepared by the electrochemical polymerization of pyrrole in a polymer matrix consisting of a metal phthalocyanine (M-Pc) and binder polymers. The gas diffusion hybrid polymer (GDHP) electrode was applied to the electrochemical reduction of oxygen. The characteristics of the electrode were studied on the basis of the catalytic activity of the M-Pc and of the oxygen gas permeability of the binder polymer. The activity of the GDHP electrode was controlled by the kind of central metal in the phthalocyanine and also by the permeability of oxygen gas in the binder polymer. The electrode reaction proceeded not only on the surface of the electrode but also in the bulk of the electrode. The reaction site of the GDHP electrodes appeared to be located at the interface of two phases (liquid/solid) and in the electrode bulk, completely different from the reaction zone (gas/liquid/solid interfaces) of conventional porous electrodes.