Nanotubes could be essential in the next generation of tiny electronic and electro-optical components; the nanotubes could contribute to faster switching times.
Nanotubes are tiny and have graphitic honeycomb lattices, they have extraordinary mechanical, thermal, and electronic properties, the Empa Swiss Federal Laboratories for Materials Science and Technology reported. The findings were published in a recent edition of the journal Nature.
The nanotubes have a diameter of only one nanometer. Even the smallest structural changes in the single-wall CNTs (or SWCNTs) could result in dramatic changes to the electronic properties. An SWCNT with one property could be metallic while one with another could act as a semiconductor. Because of this phenomenon researchers are working to make SWCNTs as structurally uniform as possible.
About 15 years ago synthesis concepts for uniformity were created, but were not implemented until now. Empa researchers and chemists at the Max Planck Institute have successfully described how to "grow" structurally homogenous SWCNTs and defined their electronic properties.
The team also looked at how to produce certain nanostructures through what is called "bottom-up" synthesis.
"The great challenge was to find the suitable starting molecule that would also actually 'germinate' on a flat surface to form the correct seed," said Roman Fasel, Head of the "nanotech@surfaces" Laboratory at Empa and Professor of Chemistry and Biochemistry at the University of Berne.
The researchers successfully synthesized a suitable starting molecule, which was a hydrocarbon with no less than 150 atoms. In order to accomplish the feat a flat starting must be morphed into a three-dimensional object called a "germling." This occurs on a hot platinum surface and through a catalytic reaction in which hydrogen atoms split into new carbon-carbon bonds. The germ is then folded out of a flat molecule; this forms the "lid" of the SWCNT.
In a second process carbon atoms are attached and position themselves between the platinum surface and the end cap. This raises the cap higher and higher, eventually resulting in a nanotube.
These findings could allow researchers to produce materials of different properties by selecting their starting molecule. In the future the team hopes to gain more insight into how SWCNTs can populate a surface.
