Single-walled carbon nanotubes have been synthesized by a gas-phase CO
decomposition (HiPCO) process, involving high-pressure disproportionation of CO as
carbon feedstock and catalytic iron particles were obtained from pyrolysis of Fe(CO)5. The
diameter and diameter distribution of as grown material dependents on various parameters,
the strong is the pressure of CO cold transverse the Fe(CO)5, nozzle geometry and position
for the injection of the reactant in the reaction chamber to produce smaller diameter (about
0.9 nm) at higher CO pressure. The HiPCO materials containing iron were purified by a
two-step process of oxidation in oxygen atmosphere and successive washing the mixture of
hydrochloric and nitric acids neutralised and distilled water (1:1:1). The optical and
electronic properties were studied using optical absorption and infrared spectroscopy; in
addition, high-resolution transmission electron energy-loss spectroscopy was used to
analyse the loss function, electron diffraction and core level excitations. The degree of
purification achieved was estimated using transmission electron microscopy. Furthermore,
the present procedure has a no sufficiently change in the diameter and diameter distribution
after Gaussian fit of the optical absorbance spectra. The estimation of the degree of
purification is possible by the analysis of core level excitation; finally high purity SWCNTs
were obtained.
