The “yield”, in compliance with the
commonly adopted definition in other works, should be calculated
from the following equation:
where mtotal and mcatalyst are the total material mass (including
catalysts) after CVD and the catalyst mass, respectively.
In Table 1, Nitze et al. used C60-supported Pd-catalyst particles to
grow HCNFs at 550 C [17]. Using Pd nanoparticles, they could grow
homogeneous CNCs with a highly periodic pitch. However, their
yield was limited to that allowed by a typical CVD method. Corrias
et al. [28] produced CNTs by a fluidized bed method in a vertical
CVD furnace. They used Fe/(Al2O3) as the catalyst particles while
mesoporous alumina (Al2O3) particles were introduced as the
initially fluidized powder. The carbon yield often exceeded 95%
with close to 100% selective growth of nanotubes.
Su et al. [20] used a simple technique that involved dissolving
ferrocene in alcohol and sprayed the solution into the horizontal
CVD reaction zone for the continuous production of high-purity
SWCNTs. Their method offered a yield of nanocarbonaceous materials
up to 50%. In contrast, the yield of our vertical CVD geometry
with Pd catalysts and the spray pyrolysis method reached about
128%.