Platinum nanowires may pave way for more efficient fuel cells

March 12th, 2009 - 2:46 pm ICT by ANI  

Washington, Mar 12 (ANI): Researchers at the University of Rochester have created long platinum nanowires that may lead to the development of commercially viable fuel cells.
It is believed that the new wires could provide significant increases in both the longevity and efficiency of fuel cells, which have until now been used largely for such exotic purposes as powering spacecraft.
Lead author James C. M. Li, professor of mechanical engineering at the University of Rochester has said that nanowire enhanced fuel cells could power many types of vehicles, helping reduce the use of petroleum fuels for transportation.
“People have been working on developing fuel cells for decades. But the technology is still not being commercialised. Platinum is expensive, and the standard approach for using it in fuel cells is far from ideal. These nanowires are a key step toward better solutions,” said Li.
Roughly 10 nanometres in diameter, the platinum nanowires are long enough to create the first self-supporting “web” of pure platinum that can serve as an electrode in a fuel cell.
The scientists used a process known as electrospinning-a technique used to produce long, ultra-thin solid fibers-to create platinum nanowires that are thousands of times longer than any previous such wires.
“Our ultimate purpose is to make free-standing fuel cell catalysts from these nanowires,” said Li.
Within a fuel cell the catalyst facilitates the reaction of hydrogen and oxygen, splitting compressed hydrogen fuel into electrons and acidic hydrogen ions.
Then the electrons are routed through an external circuit to supply power, while the hydrogen ions combine with electrons and oxygen to form the “waste” product, typically liquid or vaporous water.
The naowires completely avoid all the problems linked with using platinum nanoparticles, which were earlier used for making fuel cells.
With platinum arranged into a series of centimetre long, flexible, and uniformly thin wires, the particles comprising them are fixed in place and need no additional support. Platinum will no longer be lost during normal fuel cell operation.
“The reason people have not come to nanowires before is that it’’s very hard to make them. The parameters affecting the morphology of the wires are complex. And when they are not sufficiently long, they behave the same as nanoparticles,” said Li.
The biggest challenge that the researchers overcame was to reduce the formation of platinum beads along the nanowires.
“With platinum being so costly, it’’s quite important that none of it goes to waste when making a fuel cell. We studied five variables that affect bead formation and we finally got it-nanowires that are almost bead free,” said Li.
Now, the researchers hope to further optimise laboratory conditions to obtain fewer beads and even longer, more uniformly thin nanowires.
“After that, we”re going to make a fuel cell and demonstrate this technology,” said Li.
The study has been published in the journal Nano Letters. (ANI)

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