Nucleation and aligned growth of multi-wall carbon nanotube films during thermal CVD

The development during early growth of a multi-wall carbon nanotube film by thermal CVD with acetylene (C2H2) and hydrogen at 750 °C has been characterized in detail by cross-section transmission electron microscopy. The studies provide information on the nanotube growth mechanisms and the complex catalyst transformations that are essential for the onset of different growth stages. An initial random growth catalysed by supported particles is followed by aerosol growth of aligned tubes. This results in a two-layered film structure, where a film of aligned nanotubes is lifting up an initially formed nanotube network from the substrate.