Conducting polymer-transition metal electro-catalyst compositions for fuel cells

Abstract

An electro-catalyst composition for use as an electrode, gas diffusion layer-supported electrode, catalytic electrode-coated solid electrolyte layer, and/or membrane-electrode assembly in a proton exchange membrane (PEM) type fuel cell. The composition comprises: (a) a proton- and electron-conducting polymer having at least one heteroatom per backbone monomer unit thereof and a plurality of neutral transition metal atoms covalently bonded to at least a portion of the heteroatoms; wherein the polymer has an electronic conductivity no less than 10−4 S/cm and a proton conductivity no less than 10−5 S/cm. Preferably, the electro-catalyst composition further comprises (b) a plurality of catalytically active particles of a transition metal, nucleated around the covalently bonded transition metal atoms. Also preferably, additional catalytically active catalyst particles with an average dimension smaller than 2 nm (most preferably smaller than 1 nm) are physically dispersed in such a polymer and typically not chemically bonded thereto. A hydrogen-oxygen PEM fuel cell or a direct methanol fuel cell (DMFC) featuring such an electro-catalyst composition in a thin-film electrode exhibits a superior current-voltage response.

Dependencies are inferred from the claim text.