A study of carbon nanotube contamination by XANES spectroscopy

Abstract

Carbon-based nanostructures continue to attract a disproportionate share of research effort because of their wide range of properties. This research includes synthesis techniques and controlling the structure and morphology of nanomaterials, since for many applications tedious manipulations are often required. One of the problems faced in such a characterization is contamination. Carbon nanotubes (CNTs) have been synthesized by hot filament plasma enhanced catalytic chemical vapour deposition (HF PE CCVD) and investigated by x-ray absorption near-edge spectroscopy (XANES). The spectra showed that samples with a large surface curvature are less sensitive to thermal treatment. Among the contaminants, we find potassium, which may have come from the beam line.

Finding a needle in a chemical haystack: tip-enhanced Raman scattering for studying carbon nanotubes mixtures

“…The synthesis of carbon nanotubes is a complicated process and impurities, such as other carbonaceous materials, are sometimes formed in the process. [10,11] It has been shown that is able to provide the complete atomic structural assignment of SWCNT based on the radial breathing mode (RBM) vibrational frequency. [12] Another work has demonstrated the chirality changes in SWCNT with 40 nm spatial resolution based on both the SWCNT G bands and RBM vibrations.…”

Curvature, Hybridization and Contamination of Carbon Nanostructures Analysis Using Electron Microscopy and XANES Spectroscopy

“…The curvature of the graphite sheet is also among those factors that were considered to explain the change of the electronic states in CNSs [36]. The carbon K-edge x-ray absorption spectroscopy [21,37,38] and TEM [21,22] revealed that the features of electronic states of the carbon atoms in the carbon nanostructures are very similar to those of graphite. Thus, the CNSs XANES spectra are very similar to those of graphite and almost identical with that of HOPG (High Oriented Pirolytic Graphite) measured at the magic angle (54.7˚), where no polarization dependence of π-type states occurs.…”

“…Thus, the CNSs XANES spectra are very similar to those of graphite and almost identical with that of HOPG (High Oriented Pirolytic Graphite) measured at the magic angle (54.7˚), where no polarization dependence of π-type states occurs. Carbon K-edge x-ray absorption spectra of CNSs as observed in Figure 3, can be divided into three regions [18,21,26,37,38]. The first region is located at 285.5 eV with the peak named A.…”

“…As a consequence of this specific dimensional particularity, every nanostructure synthesized has to be characterizing for fully mastering its proprieties and by the way, handle its applications [18][19][20][21][22]. Another specificity of nanostructures is their complex and heavy synthesis processes compared to other materials used in different domains of technology and their different methods of synthesizing [23][24][25].…”

Characterization of Carbon Nanotubes

“…GISAXS is an extension of the well knows SAXS (Small Angle X-ray Scattering). XANES spectroscopy has been a powerful tool that not only provides information on the local environment around carbon, such as diamond, carbon nitride and graphitic carbon [6][7][8], but also investigates the absorption and adsorption of hydrocarbon molecules [9], radicals and atoms with specific selectivity for the orientation of these compounds. This property of XANES spectroscopy is due to the angular dependence of the absorption transition [6].…”