Patent ID: 7758921

Claim:
A method of making a membrane electrode assembly (MEA) having an anode and a cathode and a proton conductive membrane therebetween, wherein a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated in the nanotubes forms at least one portion of the MEA and is in contact with the membrane, said method comprising the steps of: (a) introducing a combination of a transition metal-containing carbon nanotube precursor and a gaseous mixture comprising an inert gas and a reducing gas into a first reactor zone maintained at a first temperature and for a period of time sufficient to vaporize the transition metal-containing carbon nanotube precursor, introducing the vaporized material to a second reactor zone maintained at a second temperature that is higher than the first temperature and for a period of time sufficient to pyrolyze the transition metal-containing carbon nanotube precursor, and grow longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes onto a substrate present in the second reactor zone, wherein the substrate is patterned with a template for forming longitudinally-aligned carbon nanotubes perpendicular to the substrate surface, and the carbon nanotube precursor is selected from the group consisting of a transition metal phthalocyanine, a transition metal porphyrin compound, a transition metal organometallic compound, or a combination thereof, optionally as a solution in an aromatic hydrocarbon solvent; (b) introducing transition metal or precious metal crystallites onto the surface of the nanotubes; (c) depositing a layer of an ionomeric polymer over the carbon nanotubes and drying the polymer to form a nanotube-containing polymeric decal having an outer polymeric side and an inner nanotube side in contact with the substrate; (d) fusing the polymeric side of two such decals to both sides of a proton-conductive membrane at an elevated temperature and pressure; and (e) removing the substrates to thereby form a MEA comprising a proton-conductive membrane core between an anode and a cathode, the anode and cathode each comprising a sheet of longitudinally aligned transition metal-containing carbon nanotubes, wherein the carbon nanotubes are aligned generally perpendicular to the membrane.