Preparation of aligned carbon nanotubes catalysed by laser-etched cobalt thin films

Pyrolysis of 2-amino-4,6-dichloro-s-triazine over laser-etched thin films of cobalt deposited on an inverted silica substrate generates aligned bundles and films of carbon nanotubes of uniform dimensions. Scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray analyses, electron energy loss spectroscopy and electron diffraction studies reveal that the aligned tubes, which usually grow perpendicular to the substrate surface, are mainly straight (length ≤100 μm; 30-50 nm OD), contain traces of nitrogen (<5%) and exhibit a preferred helicity (e.g. armchair 25-30%). Other graphitic structures (e.g. polyhedral particles, encapsulated particles and amorphous carbon) are absent. Energised cobalt clusters/particles (≤50 nm), ablated during laser-etching, may condense and recrystallise evenly on the surface of the substrate as cobalt and/or cobalt oxide. These crystals apparently play a key role in nanotube production.