Synthesis of carbon-encapsulated nanowires using polycyclic aromatic hydrocarbon precursors

A method using polycyclic aromatic hydrocarbon (PAH) precursors for synthesizing carbon nanotubes filled with pure copper or germanium is reported. A model is proposed where the interaction of small copper or germanium clusters with PAH molecules is shown to form carbon-encapsulated nanowires. The validity of this model is demonstrated by showing that filled nanotubes are formed in a hydrogen arc which produces PAH molecules when graphite electrodes are used. Alternatively, we have also used pyrene (C16H10), a PAH molecule, to grow encapsulated nanowires directly. No filled nanotubes are found in a helium arc which does not generate PAHs.