Platinumfree fuel cell

Science News,  Oct 20, 2007  by D. Castelvecchi

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Many obstacles stand in the way of ditching the internal combustion engine in favor of electric motors feeding off hydrogen fuel cells. Such a change would require new infrastructure for the delivery, storage, and distribution of hydrogen, either in a low-temperature, liquid state, or at high pressure, as a room-temperature gas. And standard hydrogen fuel cells are expensive, requiring as much as 100 grams of platinum at a cost of thousands of dollars.

A new type of fuel cell could solve both problems at once. The technology, proposed by engineers at Daihatsu, a unit of Toyota, in Ryuo, Japan, uses a fuel called hydrazine hydrate, instead of hydrogen.

Hydrazine hydrate--a compound of nitrogen, hydrogen, and water--is liquid, which makes it easier to store and deliver than gas. And it contains no carbon, so cars using it would still be environment-friendly. But perhaps the main advantage of the new fuel cell is simply that it's cheaper.

In hydrogen fuel cells, platinum serves as a catalyst membrane that breaks down hydrogen molecules into ions and electrons. The electrons provide the current that powers the car's motor. Platinum is used because it's the only metal catalyst that can survive corrosion by hydrogen ions for any length of time.

But the membrane in the Daihatsu fuel cell has to cope only with more-benign hydroxide ions, allowing engineers to use cheaper catalysts such as cobalt or nickel.

"We believe that this technology has the potential of bringing the cost of a fuel cell vehicle [down to] that of an internal combustion-engine vehicle" says team member Koji Yamada. His team's results appear in the Oct. 22 issue of Angewandte Chemic.

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