A US scientist claims to have developed a simple way to produce efficient platinum nanodots for use in fuel cell applications.

The nanodots were self-assembled by Deeder Aurongzeb of Texas Tech University through rapidly heating platinum-thin films to 700C, nanotechweb.com reports.

He found that at a critical film thickness of 2nm, the clusters form facets with multifaceted sidewalls and that as a result these structures offer a greater surface area - consequently delivering greater efficiency.

He said: "It is interesting to see a cubic close-packed metal turn into various geometric shapes, such ashexagonal, pentagonal and triangular, at high temperatures. These structures are very stable, [and] thus useful for high-temperature applications.

"Metal diffuses inside an oxide if you heat the combination to a very high temperature, so the trick is to find the right film thickness and temperature where the atomic self-diffusion is faster than the diffusion of atoms in the host.

"This is achieved by rapid thermal annealing of films at various film thicknesses and temperatures to find the exact point at which this happens."

Mr Aurongzeb has identified gas sensing and catalytic decomposition of environmentally-unfriendly material as potential uses for his approach.

He now plans to nanoalloy and layer the nanodots with alternative metals such as iridium and conducting oxides to attempt to improve his results.

Source:

Facets for fuel cells, 18/10/07
http://nanotechweb.org/cws/article/tech/31465

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