Short single-walled carbon nanotubes can be grown longer using iron catalysts docked at each end
The synthesis of single-walled carbon nanotubes (SWNTs) usually results in a mixture of both conducting and semiconducting tubes, which are hard to separate. This is a major problem with the use of SWNTs in electronic devices. In an important step forward, James Tour and co-workers1 at Rice University, Texas in the USA have developed a method that could be used to ‘amplify’ a single nanotube and make copies with the same properties as the original.
The process involves the association of iron salts with the ends of short, polymer wrapped nanotubes. When one of these modified SWNTs is deposited on a Si/SiO2 substrate and heated to remove the polymer molecules, iron oxide particles form at the ends of the tube. Treatment with hot hydrogen gas converts these into iron particles, which become ‘docked’ into the ends of the nanotubes. When reacted with a carbon source (ethylene) at 750 °C, the nanotube grew to over 6 μm long.
Because the nanotube grew in the same direction and with the same diameter as the original, this suggests that SWNT type might be conserved. Importantly, this technique may offer a way to make large amounts of type-specific SWNTs as the longer tubes can be cut up into shorter ones and the process repeated over and over again.
References
Smalley, R. E. et al. Single wall carbon nanotube amplification: En route to a type-specific growth mechanism. J. Am. Chem. Soc. 10.1021/ja065767r (2006).
Rights and permissions
About this article
Cite this article
Mantoura, S. Carbon copies. Nature Nanotech (2006). https://doi.org/10.1038/nnano.2006.177
Published:
DOI: https://doi.org/10.1038/nnano.2006.177
