This disclosure relates to fuel cell supported catalyst and methods of manufacturing the same.
Cost and durability issues have made it difficult to commercialize fuel cells. Fuel cells utilize a catalyst that creates a chemical reaction between a fuel, such as hydrogen, and an oxidant, such as oxygen, typically from air. The catalyst is typically platinum loaded onto a support, which is usually a high surface area carbon.
Some durability issues are attributable to the degradation of the support caused by corrosion. Electrochemical studies have indicated that the corrosion depends strongly on surface area and morphology structure of carbon. For example, it has been reported that carbon with high surface area, such as ketjen black, can corrode severely at potentials experienced during start and stop cycling of the fuel cell causing a dramatic loss in fuel cell performance. Accordingly, to overcome this particular durability issue, it may be desirable to use a support other than carbon that is more chemically and electrochemically stable.
One possible alternative support for a catalyst is a metal oxide or metal phosphate. Metal oxides/phosphates can typically have a high surface area and good corrosion resistance in low temperature fuel cell applications. However, most of those high surface area metal oxides/phosphates are not conductive, and are extremely hydrophilic. Hydrophilic supports can cause sever problems, such as flooding, which leads to significant drop in cell performance, especially at high current densities. As a result, metal oxide/phosphate based supported catalysts have not been applied to low temperature fuel cells.
What is therefore needed is a modified metal oxide/phosphate based supported catalyst that is suitable for use in a fuel cell environment.
A fuel cell supported catalyst is disclosed that includes an underlying support structure having at least one of a metal oxide and a metal phosphate. Catalyst particles are arranged onto and in engagement with the support structure. An intermediate conductive, corrosion-resistant layer, such as boron-doped-diamond, is arranged onto and in engagement with the support structure to surround the catalyst particles. The supported catalyst is produced by depositing the intermediate layer onto the underlying support structure after the catalyst particles have been deposited on the underlying support structure, in one example. In another example, voids are provided in the intermediate layer, which has been deposited onto the underlying support structure, to subsequently receive the catalyst particles.
These and other features of the disclosure can be best understood from the following specification and drawings, the following of which is a brief description.
a-3b illustrate a method of producing a fuel cell supported catalyst by coating a metal oxide/phosphate underlying support with a catalytic material and an intermediate layer.
a-4b illustrate another method of producing a fuel cell supported catalyst by coating a metal oxide/phosphate underlying support with a catalytic material and an intermediate layer.
a-5d illustrate yet another method of producing a fuel cell supported catalyst by coating a metal oxide/phosphate underlying support with a catalytic material and an intermediate layer.
An example fuel cell 10 is schematically illustrated in
The anode 14 and cathode 18 typically include a catalyst arranged on a catalyst support. The catalyst support provides the underlying high surface area structure upon which a controlled amount of catalyst particles are deposited. Typically, the catalyst is platinum particles and the catalyst support is carbon, such as ketjen black, carbon fibers or graphite.
This disclosure relates to a supported catalyst 30 having a metal oxide or metal phosphate underlying support structure 32, as shown in
However, metal oxides/phosphates are extremely hydrophilic, which is undesirable property in some applications due to electrode flooding, particularly in the low temperature fuel cells. In addition, undoped metal oxides/phosphates have limited electrically conductivity but catalyst supports typically must be somewhat conductive to ensure effective electron transfer within the supported catalyst structure. Otherwise the fuel cell will experience an undesirable amount of internal resistance. As a result, the supported catalyst must not only be more hydrophobic but also conductive to be suitable for use as in fuel cell. To this end, a conductive intermediate layer is deposited onto the metal oxides/phosphate underlying support structure. In one example, a boron-doped-diamond (BDD) is used as the intermediate layer. However, BDD is expensive, has limited strong-metal-support-interaction and has a low surface area. Accordingly, it is desirable to use BDD in a controlled, limited manner and deposit the catalyst particles directly onto the metal oxide/phosphate support structure. Other conductive corrosion-resistant intermediate layer materials include graphitized carbon, diamond-like carbon, carbides and conductive polymers may be substituted for the BDD.
The supported catalyst 30 includes catalyst particles 34 arranged on the metal oxide/phosphate underlying support structure 32. Example catalysts include noble metals, such as platinum, palladium, gold, ruthenium, rhodium, iridium, osmium, or alloys thereof. A secondary metal can also be used to reduce the amount of noble metal used. Example secondary metals include transition metals, such as cobalt, nickel, iron, copper, manganese, vanadium, titanium, zirconium and chromium. The catalyst particles 34 are in contact with and physically supported by the metal oxide/phosphate underlying support structure 32. An intermediate layer 36 coats the metal oxide/phosphate underlying support structure 32 such that a surface 38 of the catalyst particles 34 are exposed and extend beyond the surface 40 of the intermediate layer 36. The supported catalyst 30 described above has excellent oxygen reduction reaction activity and durability.
Several example methods of producing the supported catalyst 30 are schematically depicted in
A second production method is shown in
A third production method is shown in
Although example embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2009/033609 | 2/10/2009 | WO | 00 | 8/2/2011 |
Publishing Document | Publishing Date | Country | Kind |
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WO2010/093354 | 8/19/2010 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4643957 | Takeuchi et al. | Feb 1987 | A |
5112706 | Pinsky et al. | May 1992 | A |
5677074 | Serpico et al. | Oct 1997 | A |
5783325 | Cabasso et al. | Jul 1998 | A |
6811911 | Peled et al. | Nov 2004 | B1 |
6828056 | Molter et al. | Dec 2004 | B2 |
6884290 | Swain et al. | Apr 2005 | B2 |
7108773 | Masel et al. | Sep 2006 | B2 |
7129194 | Baca et al. | Oct 2006 | B2 |
20010000889 | Yadav et al. | May 2001 | A1 |
20030166734 | Krylova et al. | Sep 2003 | A1 |
20030166987 | Roark | Sep 2003 | A1 |
20040221796 | Swain et al. | Nov 2004 | A1 |
20050112451 | Lee et al. | May 2005 | A1 |
20060134507 | Park et al. | Jun 2006 | A1 |
20060175953 | Swain et al. | Aug 2006 | A1 |
20060188775 | Mance et al. | Aug 2006 | A1 |
20060257719 | Merzougui et al. | Nov 2006 | A1 |
20070248862 | Park et al. | Oct 2007 | A1 |
20070281204 | Uensal et al. | Dec 2007 | A1 |
20080014494 | Iordache et al. | Jan 2008 | A1 |
20080166623 | Cendak et al. | Jul 2008 | A1 |
20080194400 | Schmidt | Aug 2008 | A1 |
Number | Date | Country |
---|---|---|
0 248 386 | Dec 1987 | EP |
1883131 | Jan 2008 | EP |
2000048833 | Feb 2000 | JP |
2002200427 | Jul 2002 | JP |
2002246033 | Aug 2002 | JP |
10-2006-0071555 | Jun 2006 | KR |
WO2010033111 | Mar 2010 | WO |
WO2010033121 | Mar 2010 | WO |
Entry |
---|
International Search Report and Written Opinion of the International Searching Authority for International application No. PCT/US2009/033609 mailed Sep. 29, 2009. |
International Preliminary Report on Patentability for International application No. PCT/US2009/033609 mailed Aug. 25, 2011. |
International Application No. WO 2008/006210, Machine Translation, 6 pages. |
International Preliminary Report on Patentability, issued Mar. 22, 2011, for International Application No. PCT/US2008/076577 4 pages. |
International Preliminary Report on Patentability, issued Mar. 22, 2011, for International Application No. PCT/US2008/076948, 4 pages. |
International Search Report and Written Opinion, mailed Mar. 31, 2009, for International Application No. PCT/US2008/076948, 10 pages. |
International Search Report, mailed Mar. 31, 2009, for International Application No. PCT/US2008/076577, 2 pages. |
Young, “Miniature Fuel Cell Harnesses the Power of Bee Venom,” Apitherapy News, 2007, 1 page. |
U.S. Appl. No. 13/057,198, filed Feb. 2, 2011, Fuel Cell Catalyst Support With Fluoride-Doped Metal Oxides/Phosphates and Method of Manufacturing Same. |
U.S. Appl. No. 13/057,308, filed Feb. 3, 2011, Fuel Cell Catalyst Support With Boron Carbide-Coated Metal Oxides/Phosphates and Method of Manufacturing the Same. |
Number | Date | Country | |
---|---|---|---|
20120021337 A1 | Jan 2012 | US |