Pure Nanotubes by the Kilo

Technology Review
July 21, 2011

An improved process for making large amounts of pure metallic carbon nanotubes could hold the key to overhauling the electrical power grid with more efficient transmission lines.

Researchers at Rice University in Houston plan to generate a large quantity of this material by the end of summer. They'll use these nanotubes to make long and highly conductive fibers that could be woven into more efficient electrical transmission lines.

There are a few different classes of carbon nanotube, each with slightly different properties and different potential uses. Unfortunately, existing production methods result in a mixture of different nanotubes, with varying dimensions and wildly different electrical properties. Purely semiconducting nanotubes, useful for future integrated circuits, are in the mix with metallic nanotubes that could be used to make highly conductive wires. So nanotubes have to be separated by type, a slow and expensive process, says Andrew Barron, professor of chemistry and materials science at Rice.

"There is a subset of nanotubes that are the best conducting materials to be found, that don't lose any energy to heat," says Barron.

Barron is part of a group at Rice that wants to make something very large from these nanotubes: miles and miles of highly conductive electrical transmission lines for a more efficient energy grid, which will be important as the use of renewable energy grows. This was one vision of the late Rice professor Richard Smalley, who won the Nobel Prize in Chemistry for his codiscovery of carbon nanomaterials. The Rice researchers have made long, pure carbon nanotube fibers, but since they have been working from impure samples, these fibers are not as conductive as they could be.
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