Carbon nanotube conductors

Researchers at the Honda Research Institute

, with support from academics at

and

, have been assessing nanotubes and their potential to transport electricity faster over large distances with minimum energy loss.

The carbon nanotubes may open up new possibilities for more powerful and compact fuel cells, energy storage materials and hybrid vehicles.

Grown on the surface of metal nanoparticles, they take the form of rolled honeycomb sheets with carbon atoms in their tips.

Researchers at Purdue University used a transmission electron microscope to observe nanotube formation, revealing that changes in the gaseous environment can vary the shape of the metal catalyst nanoparticles from very sharp faceted to completely round.

Further work carried out at Louisville produced the nanotubes in larger volumes and made measurements to determine whether the nanotubes achieve a metallic state.

According to the researchers, the carbon nanotube formation revealed metallic conductivity that was significantly stronger when compared to steel, had higher electrical properties than copper, was as light as cotton and could conduct heat as efficiently as a diamond.

Dr Avetik Harutyunyan, principal scientist from Honda Research Institute USA, said: ‘This is the first report that shows we can control fairly systematically whether carbon nanotubes achieve a metallic state. Further research is in progress with the ultimate goal to take complete control over grown nanotube configurations to support their real-world application.’

Dr Harutyunyan added: ‘Our finding shows that the nanotube configuration that defines its conductivity depends not only on the size of the metal nanocatalyst used to nucleate the tube as was previously believed, but, importantly, is also based on its shape and crystallographic structure, and we learned to control it.’

Up until now, research had focused on the structural formation of carbon nanotubes with metallic conductivity through conventional methodology resulting in a success rate of around 25 to 50 per cent. Honda claims that it has achieved a success rate of 91 per cent metallic conductivity.

Dr Hideaki Tsuru, project director from Honda Research Institute USA, said: ‘Our goal is not only the creation of new and better technologies and products, but to fulfil Honda’s commitment to environment sustainability.’