Nanotubes Go for Gold


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Prof. Ernesto Joselevich and Tohar Yarden. Golden touch



King Midas may have turned everything he touched to gold, but he never got his hands on carbon nanotubes. That feat has been left to Prof. Ernesto Joselevich and research student Tohar Yarden of the Chemistry Faculty’s Materials and Interfaces Department. The two recently applied a technique, developed in Joselevich’s lab for directing the production of carbon nanotubes, to create, among other things, intricately shaped gold nanowires.
Two years ago, Joselevich and his research team began fabricating long, thin carbon nanotubes that bend, loop and curve into various shapes, including radiator-like serpentines that hinted at possible uses in nanodevices. Interestingly enough, these tiny shapes are self-organizing. By creating a sort of “ordered chaos,” in which fluctuations drive tube formation, the scientists found it was possible to “draw” any pattern they desired with these continuous carbon nanotubes.
Gold-plated serpentine carbon nanotubes


Now, the scientists have begun gold-plating these nanotube shapes through a process called electrodeposition. Electrical pulses cause dissolved metal salts to leave the solution and attach to the nanotubes. Lovely as these creations appear, the idea is not to design microscopic jewelry, says Joselevich, but “to combine the unique geometry of the serpentine nanotubes with the properties of other materials.” Any material that is a conductor or semiconductor can be used to make nanowires with this method, which, in their recent publication in Nano Letters, the researchers called "drawing with nanotubes.” In addition to gold, they coated serpentine nanotubes with bismuth telluride, a material that has the ability to convert heat to electricity or, conversely, cool when electricity passes through. Nanowires of bismuth telluride could power microscopic devices or function as miniature cooling units for nanoelectronics.
The team is continuing to experiment with creating serpentine nanowires from a variety of materials. A recent effort might be used, for instance, in miniature light collectors or sensors, or even “nano-neon” lights.
Prof. Ernesto Joselevich's research is supported by the Carolito Stiftung.