Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

• US 20060269827A1
• Filed: 03/03/2006
• Published: 11/30/2006
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: U Chicago Argonne, LLC
• Original Assignee: University of Chicago
• Inventors: Yang, Junbing, Liu, Di-Jia
• Granted Patent: US 7,758,921 B2
• Time in Patent Office: Days
• US Class Current: 429/483
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 4/9008 Organic or organo-metallic compounds
• CPC Class Codes: H01M 8/04194 Concentration measuring cells
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A method of making a membrane electrode assembly (MEA) having an anode and a cathode and a proton conductive membrane there between. 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. A combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into a first reaction zone maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is transmitted to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes. The nanotubes are in contact with a portion of the MEA at production or being positioned in contact thereafter. Methods of forming a PEMFC are also disclosed.

Claims

1. 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 introducing a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas into a first reaction zone maintained at a first reaction temperature for a time sufficient to vaporize material therein, introducing the vaporized material to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, the nanotubes being in contact with a portion of the MEA at production or being positioned in contact thereafter.

2. The method of claim 1, wherein a substrate is present in the second reaction zone and has a predetermined pattern thereon prior to formation of the longitudinally aligned carbon nanotubes thereon to cause the carbon nanotubes to form a preselected pattern on the substrate.

3. The method of claim 1, wherein the vapor in the first reaction zone contains one or more of argon and hydrogen and ammonia and a nitrogen-containing hydrocarbon and an organometallic compound of Fe or Ni or Co or Cr or Mn or mixtures thereof.

4. The method of claim 1, wherein the temperature in the first reaction zone is maintained in the range of from about 150°

C. to about 700°

C. and the temperature in the second reaction zone is maintained in the range of from about 700°

C. to about 1000°

C.

5. The method of claim 1, wherein material is maintained in the reaction zones for a time in the range of from about 5 to about 45 minutes.

6. The method of claim 1, wherein the organic moiety of the organometallic compound is one or more of the compounds in Table 1.

7. The method of claim 1, wherein the nanotubes form a three dimension (3D) pattern.

8. The method of claim 2, wherein the substrate has thereon or therien a 3D pattern prior to the formation of the nanotubes.

9. The method of claim 1, wherein a substrate is in the second reaction zone for the deposition of the aligned carbon nanotubes thereon, applying a layer of a suitable polymer to the nanotubes and fusing the polymer to the membrane at an elevated temperature and/or pressure to provide contact between the membrane and the nanotubes.

27. A MEA made according to the method of claim 1.

10. A method of forming a membrane electrode assembly (MEA) for a proton exchange membrane fuel cell (PEMFC), comprising forming an assembly of an anode and a cathode and a proton conductive membrane therebetween, forming longitudinally aligned graphitic nanotubes with a catalytically active transition metal incorporated in the nanotubes on one or more of the cathode or the anode by chemical vapor deposition (CVD), at least some of the graphitic nanotubes being in contact with the membrane.

11. The method of claim 10, wherein the transition metal is one or more of Fe, Ni, Co or mixtures thereof.

12. The method of claim 10, wherein the nanotubes are generally straight or include spiral or bamboo shaped or bellows shaped nanotubes.

13. A method of forming a combination of longitudinally aligned graphitic nanotubes with a catalytically active transition metal incorporated in the nanotubes in contact with one or more of a cathode or an anode and in contact with the proton conductive membrane, comprising preparing longitudinally aligned graphitic nanotubes with a catalytically active transition metal incorporated in the nanotubes by CVD and having a portion thereof in contact with one or more of the cathode or the anode and in contact with the proton conductive membrane and arranging a layered combination of the anode and cathode separated by the membrane, the longitudinally aligned graphitic nanotubes being generally perpendicular to the membrane.

14. The method of claim 13, wherein the transition metal is one or more of Fe, Ni, Co or mixtures thereof.

15. The method of claim 14, wherein most of the transition metal is chemically associated with nitrogen.

16. The method of claim 15, wherein the vapor deposited by CVD includes one or more of an organometallic compound and a hydrocarbon compound and a nitrogen containing compound and a reducing material and an inert gas.

17. The method of claim 16, wherein the organometallic compound is selected from Table 1 and the reducing material is hydrogen and the nitrogen containing compound is ammonia and the inert gas is argon.

18. The method of claim 17, wherein the CVD occurs in one zone of a multiple zone reactor.

19. The method of claim 18, wherein the nanotubes are supports for either an oxidation catalyst or a reduction catalyst.

20. The method of claim 19, wherein the catalyst is an oxidation catalyst formed on the cathode.

21. The method of claim 19, wherein the catalyst is a reduction catalyst formed on the anode.

22. The method of claim 13, wherein a plurality of the layered combinations are assembled into a PEMFC.

28. A combination of longitudinally aligned grahitic nanotubes made according to the method of claim 13.

23. A method of forming a membrane electrode assembly (MEA) for a proton exchange membrane fuel cell (PEMFC), comprising forming an assembly of an anode and a cathode and a proton conductive membrane therebetween, forming longitudinally aligned graphitic nanotubes on one or more of the cathode or the anode by chemical vapor deposition (CVD), at least some of the graphitic nanotubes being in contact with the membrane.

29. A MEA made according to the method of claim 23.

24. A method of forming a membrane for a proton exchange membrane fuel cell (PEMFC), comprising providing a proton conductive membrane, forming longitudinally aligned graphitic nanotubes with a catalytically active transition metal in the nanotubes on a substrate by chemical vapor deposition (CVD), transferring the longitudinally aligned graphitic nanotubes from or with the substrate to the proton exchange membrane with the longitudinally aligned graphitic nanotubes being generally perpendicular to the proton exchange membrane and in contact therewith.

25. The method of claim 24, wherein the substrate is a cathode or an anode and most of the nanotubes are in contact with the membrane and the cathode or the anode.

26. The method of claim 24, wherein the nanotubes are transferred by forming a layer of a suitable polymer on the nanotubes and hot pressing the layer with the nanotubes onto the membrane and thereafter removing polymer from the membrane where possible.

30. A membrane made according to the method of claim 24.