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October 10, 2006
Los Alamos Laboratory scientists develop cheaper fuel cell catalyst
(Comtex Energy Via Thomson Dialog NewsEdge) BERKELEY, Calif., Oct 10, 2006 (Daily Californian, U-WIRE via COMTEX) --Scientists are now one step closer to developing cheaper fuel cells after making a discovery at a lab with a 30-year history of fuel cell research.
Sponsored by the U.S. Department of Energy, scientists at Los Alamos National Laboratory have developed a catalyst that uses a cobalt compound in fuel cells instead of platinum, which is currently the most expensive part of the cells, said Piotr Zelenay, one of the researchers.
"There is a strong push in fuel cell research to replace platinum," he said. "Right now, the cost of platinum in a fuel cell stack is half the price of the stack itself."
A fuel cell provides electricity by combining fuel-usually hydrogen gas or methanol-with oxygen, to create water or carbon dioxide. The reaction occurs only with the help of a catalyst, which has traditionally involved platinum, Zelenay said.
Zelenay and his research partner Rajesh Bashyam studied catalysts in polymer electrolyte fuel cells, which are a kind of cell that could be used to power cars and homes.
The high price of platinum-currently $38 per gram-has been a limiting factor in the development and use of these fuel cells, he said.
"Prices have risen, especially over the past seven years," Zelenay said. "In 1999, it was a third of what it is today."
Alternative catalysts using nonprecious metals have tended to dissolve in the acidic environment of a polymer electrolyte fuel cell, Zelenay said.
Rajesh Bashyam said he had previous experience with such catalysts as a post-doctoral student in Switzerland.
"The problem is with the stability of the catalyst," he said.
Zelenay and Bashyam said they knew that cobalt and other transition metals would form bonds with nitrogen in a way that might make them more stable, Zelenay said.
While the cobalt compound did turn out to be stable, the researchers are still unclear as to what exactly accounts for the stability, he said.
"The original idea was simple-minded," he said. "But the detailed mechanism for stability was more complex than we thought."
The findings were published recently in the journal Nature and have gained the attention of other fuel cell researchers, Zelenay said.
"It's a big deal for the community," he said. "No material before this has been found that has stability."
Though fuel cell stacks using the cobalt compound are cheaper and perform stably, their activity is not yet superior enough to replace traditional fuel cells using platinum, Zelenay said.
"We need to increase the activity by a factor that would make it practical," he said. "Right now, if they were used in a car, the stack would be prohibitively thick."
The researchers said the answer was to understand the nature of the cobalt catalyst in order to improve its activity.
"The linkage of cobalt and nitrogen is still under question," Bashyam said. "The next step is to understand the catalyst more and test its performance."
Once they understand the catalyst better, the researchers will be able to modify the form and structure of the fuel cell in order to increase its activity, Zelenay said.
As platinum supplies continue to diminish, Bashyam said interest in nonplatinum catalysts will remain high.
"There is a lot of pressure to work more on this, and investigate these materials," he said.
The pair plans to continue research on the cobalt catalyst and said they hope to publish another paper when more details about the catalyst's characteristics are known.
Copyright (C) 2006 Daily Californian via U-WIRE
(source: http://www.tmcnet.com/usubmit/2006/10/10/1969463.htm)
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