Purification and defect elimination of single-walled carbon nanotubes by the thermal reduction technique

Abstract

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.

Numerical Analysis of the Structural Stability of Ideal (Defect-Free) and Structurally and Morphologically Degenerated Homogeneous, Linearly- and Angle-Adjoined Nanotubes and Cylindrical Fullerenes Under Axial Loading Using Finite Element Method

“…The aim of this study is to simulate mechanical properties of imperfect types of low-dimensional carbon models, which are more likely to be found in nature [Tran and Lambrakos, 2005;Sridhar et al, 2012;Miralles et al, 2012;Bokova-Sirosh et al, 2016]. The planned approach is to explore and predict the buckling response of common SWCNTs and their corresponding degenerated counterparts under the influence of atomic impurities as well as under different boundary conditions.…”

Carbon Nanotubes and Graphene Nanoribbons: Potentials for Nanoscale Electrical Interconnects

“…Thermal annealing at high temperature has been proposed as an effective method to reduce defects in nanotubes [83][84][85][86]. Annealing at different high temperatures (>1000 °C) of CVD-grown multi-wall carbon nanotubes at relatively low temperatures (650 °C) in porous alumina template lead to a different degree of rearrangement of the imperfect graphitic structure and removal of weakly bounded defects, leading to the reconstruction of the hexagonal carbon lattice along the shell in a more ordered fashion.…”

“…Thermal reduction can also be used to purify and reduce chemical defects in the carbon lattice of single-wall carbon nanotubes, where a combination of first a high-temperature reactions in as-grown nanotubes in a pressurized chamber with a slow annealing process in vacuum environment is used [84]. Application of a rapid large bias across two terminals of a carbon nanotube not only decreases contact resistance, but also can dramatically reduce the number of defects.…”

Investigation of Fe/MgO Catalyst Support Precursors for the Chemical Vapour Deposition Growth of Carbon Nanotubes

“…In addition to X-ray diffraction (XRD), differential thermal analysis (DTA) was also used. [32][33][34] Figure 11 shows the DTA results for raw MgO material and, for comparison, MgO stirred for 12 hours in water at 90 C (in order to produce directly the hydroxide) and then dried. indicates that the raw material has absorbed H 2 O from the atmosphere which is released from the structure between 250-420 C during two main steps.…”