The effect of arc parameters on the growth of carbon nanotubes

The influence of starting carbon material on the generation of carbon nanotubes is investigated. Comparisons are made between oriented graphite, randomly oriented graphite, carbon black, and a polycyclic aromatic hydrocarbon as carbon sources in helium and hydrogen arcs. Transmission electron microscopy investigation of the redeposited rod formed on the cathode and the soot from the chamber walls provides evidence for the building blocks that lead to the nanostructures formed. It is postulated that polycyclic aromatic hydrocarbons are precursors for carbon nanotube growth in a hydrogen are. While, in the case of helium, low molecular weight carbon ions and molecules have been previously hypothesized by others to be the building blocks for nanotube growth.