Carbon nanotubes have been a hot topic in material science for decades. They can be used in the construction of hard, lightweight materials or a host of optical, electronic, and thermal applications. They can act as thermal conductors in one direction (along the tube) and insulators in the other (across the tube) to give just one example of their odd properties. There have even been claims of nanotubes having a natural superconductivity, though the results have yet to be replicated. But creating a large number of homogenous nanotubes without defects is difficult and expensive.
A team of researchers at Empa and the Max Planck Institute for Solid State Research have figured out how to grow homogenous, single walled carbon nanotubes (they also come in the multi-walled variety) from a molecular seed on a hot platinum surface.
“The great challenge was to find the suitable starting molecule that would also actually ‘germinate’ on a flat surface to form the correct seed,” says Roman Fasel, Head of the nanotech@surfaces Laboratory at Empa and Professor of Chemistry and Biochemistry at the University of Berne. The research is being published in the most recent edition of Nature.
Seed molecule creates the end of the tube, ethylene provides material for the rest
The process works by placing the flat seed molecule on the platinum surface where it twists itself into the shape of a cap. After that the catalytic decomposition of ethylene on the surface of the platinum supplies more carbon atoms to be added to the bottom of the nanotube so that it continues to grow out from the surface in a predictable manner, which explains why the carbon nanotubes that result from this process are so homogenous.
EMPA will continue experimenting with seed molecules and carbon nanotubes
The EMPA process have been shown to produce carbon nanotubes of at least 300 nanometers in length. That’s not terribly long (other methods can produce nanotubes as much as half a meter in length), but it’s also just the beginning and Fasel’s team will continue to work on creating carbon nanotubes and other structures using seed molecules. They’ve already managed to make a couple of other structures including buckeyballs, which EMPA describes as ‘CNTs shrunk into ball form,’ and flat nanoribbons, and are now aiming for more complex structures.