Carbon based electrocatalysts for fuel cells

Abstract

Novel proton exchange membrane fuel cells and direct methanol fuel cells with nanostructured components are configured with higher precious metal utilization rate at the electrodes, higher power density, and lower cost. To form a catalyst, platinum or platinum-ruthenium nanoparticles are deposited onto carbon-based materials, for example, single-walled, dual-walled, multi-walled and cup-stacked carbon nanotubes. The deposition process includes an ethylene glycol reduction method. Aligned arrays of these carbon nanomaterials are prepared by filtering the nanomaterials with ethanol. A membrane electrode assembly is formed by sandwiching the catalyst between a proton exchange membrane and a diffusion layer that form a first electrode. The second electrode may be formed using a conventional catalyst. The several layers of the MEA are hot pressed to form an integrated unit. Proton exchange membrane fuel cells and direct methanol fuel cells are developed by stacking the membrane electrode assemblies in a conventional manner.

1 - 20 . (canceled) 
     
     
         21 . An electrode, comprising a catalyst layer coated proton exchange membrane;
 wherein the catalyst layer has an oriented film of a platinum-deposited carbon-based material;   wherein the carbon-based material is selected from the group consisting of dual-walled carbon nanotubes, nanofibers and cup-stacked carbon nanotubes;   wherein the catalyst layer is prepared using an ethylene glycol reduction method.   
     
     
         22 . The electrode of  claim 21 , wherein the catalyst is formed by using ethylene glycol to deposit platinum onto the carbon-based material. 
     
     
         23 . The electrode of  claim 21 , wherein the catalyst is further formed by depositing ruthenium onto the carbon-based material. 
     
     
         24 . The electrode of  claim 23 , wherein the catalyst is further formed by depositing solubilized perfluorosulfonate ionomer onto the carbon-based material. 
     
     
         25 . A membrane electrode assembly for a fuel cell formed according to the following steps:
 forming a first catalyst by depositing platinum onto a carbon-based material;   filtering the first catalyst onto a substrate to form a filtered first catalyst having an oriented film of a platinum-deposited carbon-based material;   providing a free standing proton exchange membrane;   transferring the filtered first catalyst having an oriented film of a platinum-deposited carbon-based material onto a first side of the proton exchange membrane to form a catalyst layer coated membrane;   placing a second catalyst coated second gas diffusion layer adjacent to a second side of the proton exchange membrane;   placing a first gas diffusion layer adjacent the first catalyst layer on the first side of the proton exchange membrane; and   using heat and pressure to seal the first gas diffusion layer, the first catalyst layer coated membrane, the second catalyst coated second gas diffusion layer together to produce the membrane electrode assembly.