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.