Single-walled carbon nanotube growth using [Fe(3)(mu(3)-O)(mu-O(2)CR)(6)(L)(3)](n+) complexes as catalyst precursors

We present herein the VLS growth of SWNTs from oxo-hexacarboxylate-triron precursors, [Fe(3)O(O(2)CCH(3))(6)(EtOH)(3)] and [Fe(3)O(O(2)CCH(2)OMe)(6)(H(2)O)(3)][FeCl(4)], on spin-on-glass surfaces, using C(2)H(4)/H(2) (750 degrees C) and CH(4)/H(2) (800 and 900 degrees C) growth conditions. The SWNTs have been characterized by AFM, SEM and Raman spectroscopy. The characteristics of the SWNTs are found to be independent of the identity of the precursor complex or the solvent from which it is spin-coated. The as grown SWNTs show a low level of side-wall defects and have an average diameter of 1.2-1.4 nm with a narrow distribution of diameters. At 750 and 800 degrees C the SWNTs are grown with a range of lengths (300 nm-9 microm), but at 900 degrees C only the longer SWNTs are observed (6-8 microm). The yield of SWNTs per unit area of catalyst nanoparticle decreases with the growth temperature. We have demonstrated that spin coating of molecular precursors allows for the formation of catalyst nanoparticles suitable for growth of SWNTs with a high degree of uniformity in the diameter, without the formation of preformed clusters of a set diameter.     

Epoxidation and deoxygenation of single-walled carbon nanotubes: quantification of epoxide defects

Epoxidation of single-walled carbon nanotubes (SWNTs) may be carried out by the reaction of SWNTs with either trifluorodimethyldioxirane or 3-chloroperoxybenzoic acid; the resulting O-SWNTs are spectroscopically similar to those formed by ozonolysis. Quantification of the epoxide substituents is possible through the catalytic de-epoxidation reaction using MeReO3/PPh3 and the 31P NMR spectroscopy. The de-epoxidation methodology may be used to determine that wet air oxidation is preferable to either acid or O2/SF6 purification. We have demonstrated that previously assumed "pure" SWNTs are actually "doped" to a level of at least 1 oxygen per 250 carbon atoms.