this problem. It can be inferred that the gas-flow fields, associated
heat, and mass transfer in the vertical CVD reactor were more
complex than in the horizontal CVD reactor.
We speculated that the appearance of this octopus-tentacle-like
structure was due to the following mechanism: some straight CNTs
were preformed at the 700 C zone in the chamber; when they fell
into the lower zones with lower temperatures, the decomposed
carbon atoms at 650 C or 600 C deposited on the surface of the
preformed CNTs, thus forming this special octopus-tentacle-like
structure. We have yet to determine the optimal application for
this carbon structure. However, the hollow center and the rough
and wavy wall surfaces of the octopus-tentacle-like structure can
provide a specific surface area substantially larger than those of
CNTs and CNCs, which suggests various potential applications such
as hydrogen storage media, microwave absorbers, microsensors,
and catalyst supports.
4. Conclusion