Fullerenes and their derivatives are promising materials for supercapacitor devices due to their unique nanostructure that combines the reversible redox charge storage with the high surface area. In this article, the reversible redox charge storage of C 60 , C 70 , and La@C 82 in liquid ammonia solution is reported. An electrochemical analysis of these species using cyclic voltammetry is presented in conjunction with the theoretical interpretation. The relative magnitudes of transfer coefficients, which represent a measure of the symmetry of the energy barrier for oxidation and reduction of the monoanionic species of these fullerenes, suggest that the availability of the surface area permitting delocalization of p electrons is a determining factor of their first reduction potential. The relationship between these transfer coefficients and fullerene geometry also support previous conclusions that the La atom is located within the fullerene cage of La@C 82 . The electrochemical measurements analyzed were made using a modified three-compartment cell. Advantages associated with this modified cell for analysis of capacitance characteristics of C 60 , C 70 , and La@C 82 are discussed.
A thermal reduction (TR) technique is used to purify single-walled carbon nanotubes
(SWNTs) and to reduce chemical defects from their lattice structure. This technique is
mainly comprised of two processes, high-temperature reactions of raw SWNTs in
a pressurized hydrogen chamber followed by a slow annealing under vacuum.
Analyses by TEM, TGA, XRF, and XRD of SWNT samples before and after the
purification reveal that over 90% of the carbonaceous impurities formed during the
syntheses of SWNTs (by carbon arc, laser ablation, and HiPCO) are eliminated.
Post-purification IR spectroscopic analyses show no evidence of hydrogen in the SWNT
samples and AFM studies suggest that the samples contain very few chemical
defects. In addition, analyses by TEM and Raman spectroscopy do not reveal
any significant structural damage of the SWNTs purified by the TR technique.
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