Metal and metal oxide catalyzed electrodes for electrochemical cells,

Abstract

Porous electrodes for use in fuel cells and other electrochemical cells are disclosed. Principally, the electrodes a catalytically active layer on a porous conductive substrate, which catalytically active layer is derived from non-noble metals. The loading of the catalytically active layer is lower in terms of weight of catalyst per unit area of geometrical electrode surface than heretofore. Several alternative methods of forming the electrode are taught, including impregnating a porous conductive substrate with a metal salt solution, followed by chemical or thermal formation of the porous catalytically active layer; or mixing the catalytically active material with the material of the porous conductive substrate, followed by fabrication of the electrode; or depositing pyrolitic carbon from the gas phase onto a porous conductive substrate, at elevated temperatures in a gas atmosphere. The electrode may also have a porous metallic current collector, and also a further gas diffusion layer. If used as a fuel cell anode, a further small amount of noble metal is included in the porous catalytically active layer. Porous electrodes of this invention have particular utility in alkaline primary or secondary cells as auxiliary gas recombining electrodes, especially as oxygen consuming auxiliary transfer electrodes.