Morphology study of carbon nanospecies grown on carbon fibers by thermal CVD technique

Multiwalled carbon nanotubes were uniformly grown directly on Ni catalyzed carbon fibers by catalytic decomposition of acetylene at 700 °C using thermal chemical vapour deposition process. Different process parameters such as growth temperature, time and gas flow rates were investigated in relation to morphology and yield of the products. The overall yield of the nanospecies demonstrated an initial nonlinear increase and eventually stabilized with increasing deposition time while it was found reaching to maxima at 700 °C and drops rapidly at temperatures on either side. The morphology of nanostructures was examined extensively using scanning and transmission electron microscopy which revealed formation of various carbon nanostructures such as nanofilaments, nanofibers, nanoladders, nanospirals, nanojunctions, nanocones, nanoonions etc. accompanying nanotubes. High resolution transmission electron microscopy images clearly showed single crystal structure of the catalyst particle and tip-growth mechanism of carbon nanotubes growth. Non-tip growth mechanism was observed in especial case of ferrocene derived floating Fe catalyst.