Membrane electrode assembly with enhanced start-up and shut-down durability

Abstract

A membrane electrode assembly (MEA) includes a membrane, a cathode catalyst layer, a cathode co-catalyst layer including a hydrogen reservoir, an anode catalyst layer, and an anode co-catalyst layer including a hydrogen reservoir. The anode co-catalyst layer and the cathode co-catalyst layer cap a cathode potential at lower than 1.5V and an anode potential at lower than 1.0V. The anode co-catalyst layer and the cathode co-catalyst layer can include a platinum doped rare earth oxide, such as platinum doped cerium oxide.

What is claimed is: 
     
         1 . A membrane electrode assembly, comprising:
 a proton exchange membrane disposed between two electrode layers, wherein one of the electrode layers includes a catalyst including a noble metal; and   a co-catalyst including a noble metal doped rare-earth oxide.   
     
     
         2 . The membrane electrode assembly of  claim 1 , wherein the noble metal doped rare-earth oxide includes platinum doped cerium oxide. 
     
     
         3 . The membrane electrode assembly of  claim 1 , wherein the noble metal doped rare-earth oxide is provided as a layer adjacent one of the electrode layers. 
     
     
         4 . The membrane electrode assembly of  claim 1 , wherein the noble metal doped rare-earth oxide is integrated into one of the electrode layers. 
     
     
         5 . The membrane electrode assembly of  claim 1 , wherein the two electrode layers include an anode layer and a cathode layer, the noble metal doped rare-earth oxide is integrated into the anode layer, integrated into the cathode layer, or is provided as a separate co-catalyst layer with the anode layer or the cathode layer. 
     
     
         6 . The membrane electrode assembly of  claim 1 , wherein the noble metal is disposed on a carbon support and the noble metal includes platinum. 
     
     
         7 . The membrane electrode assembly of  claim 6 , wherein one of the electrode layers includes the noble metal doped rare-earth oxide disposed on the carbon support. 
     
     
         8 . The membrane electrode assembly of  claim 7 , wherein the carbon support is in a form of particles. 
     
     
         9 . The membrane electrode assembly of  claim 8 , wherein the catalyst and the noble metal doped rare-earth oxide are disposed on different particles. 
     
     
         10 . The membrane electrode assembly of  claim 8 , wherein the catalyst and the noble metal doped rare-earth oxide are disposed on same particles. 
     
     
         11 . The membrane electrode assembly of  claim 1 , wherein each electrode layer includes an ionomer. 
     
     
         12 . The membrane electrode assembly of  claim 11 , wherein the ionomer is configured to allow a proton to travel through the electrode layers. 
     
     
         13 . The membrane electrode assembly of  claim 1 , wherein:
 the electrode layers include an anode layer and a cathode layer, the anode layer including a catalyst including platinum disposed on a carbon support;   the noble metal doped rare-earth oxide includes platinum doped cerium oxide; and   the noble metal doped rare-earth oxide is provided as a layer adjacent the anode layer or the noble metal doped rare-earth oxide is integrated into the anode layer.   
     
     
         14 . The membrane electrode assembly of  claim 13 , wherein the noble metal doped rare-earth oxide is integrated into the anode layer, the carbon support is in a form of particles, and the catalyst and the noble metal doped rare-earth oxide are disposed on same particles. 
     
     
         15 . The membrane electrode assembly of  claim 13 , wherein the noble metal doped rare-earth oxide is integrated into the anode layer, the carbon support is in a form of particles, and the catalyst and the noble metal doped rare-earth oxide are disposed on different particles. 
     
     
         16 . A fuel cell comprising a membrane electrode assembly according to  claim 1 . 
     
     
         17 . A fuel stack comprising a fuel cell including a membrane electrode assembly according to  claim 1 . 
     
     
         18 . A vehicle comprising a fuel cell including a membrane electrode assembly according to  claim 1 . 
     
     
         19 . A method of operating a fuel cell, the method comprising:
 providing the fuel cell including a membrane electrode assembly, the membrane electrode assembly including:
 a proton exchange membrane disposed between two electrode layers, wherein one of the electrode layers includes a catalyst including a noble metal; and 
 a co-catalyst including a noble metal doped rare-earth oxide; and 
   switching the fuel cell from one of a start-up state and a shut-down state to the other of the start-up state and the shut-down state, wherein the noble metal doped rare-earth oxide provides a reservoir of hydrogen.   
     
     
         20 . The method of  claim 19 , wherein:
 the electrode layers include an anode layer and a cathode layer, the anode layer including a catalyst including platinum disposed on a carbon support;   the noble metal doped rare-earth oxide includes platinum doped cerium oxide; and   the noble metal doped rare-earth oxide is provided as a layer adjacent the anode layer or the noble metal doped rare-earth oxide is integrated into the anode layer.