HOMOGENEOUS AND HETEROGENEOUS CATALYTIC REACTIONS IN COBALT OXIDE GRAPHITE AIR ELECTRODES .3. DEPOSITION OF COBALT OXIDE CATALYSTS ONTO GRAPHITE-ELECTRODES FOR OXYGEN REDUCTION

Cobalt oxide catalysts can be deposited onto the surface of Teflon-bonded graphite electrodes during oxygen reduction in HCoO2−-saturated KOH solutions. The Co3O4/graphite electrodes prepared in this way are highly active for oxygen reduction, and the performance is comparable with conventional 20 weight percent (w/o) CO3O4/graphite electrodes prepared from Co3O4-graphite mechanical mixtures. It has been found that the performance deterioration in the initial period of the long-term galvanostatic polarization is mainly due to the gradual dissolution of cobalt oxide catalysts into the solution. However, it has been shown that the in situ deposition method can replenish the cobalt oxide lost by dissolution and therefore arrest performance deterioration. The feasibility of regeneration of transition metal oxides/graphite electrodes in alkaline solutions has been demonstrated. © 1990, The Electrochemical Society, Inc. All rights reserved.