The formation mechanism of the coaxial carbon–metal nanowires in a chemical vapor deposition process

In the synthesis of carbon nanotubes from ethylene decomposition by a Fe/Mo/Al2O3 catalyst at 823 K, the long and continuous coaxial carbon–metal nanowires up to 540 nm is observed. And for the first time, it is observed that the coaxial carbon–metal nanowires can grow in tip and base growth mode simultaneously. A detailed formation mechanism is proposed, where the aggregation of metal particles, lift-up of nanotubes obeying different growth modes and the deformation of metal particles by nanotubes are considered as the necessary steps for the formation of the nanowires.