Open AccessInvestigation of Different Pre-Treated Multi-Walled Carbon Nanotubes by Raman Spectroscopy
Author(s) -
Pascal Düngen,
Marina Prenzel,
Casey Van Stappen,
Norbert Pfänder,
Saskia Heumann,
Robert Schlögl
Publication year - 2017
Publication title -
materials sciences and applications
Language(s) - English
Resource type - Journals
eISSN - 2153-1188
pISSN - 2153-117X
DOI - 10.4236/msa.2017.88044
Subject(s) - raman spectroscopy , materials science , carbon nanotube , phonon , carbon fibers , amorphous carbon , spectroscopy , raman scattering , amorphous solid , molecular dynamics , molecular vibration , chemical physics , nanotechnology , chemical engineering , composite material , computational chemistry , crystallography , condensed matter physics , optics , composite number , chemistry , physics , engineering , quantum mechanics
Raman spectroscopy is a common method of studying carbon-based materials such as multi-walled carbon nanotubes (MWCNT). However, the analysis of this technique is non-trivial since recorded spectra may be a convolution of both molecular vibrations and phonon resonances. The energies of these physical processes may occur in the same energy regime, and hence several analytical approaches can be necessary for a full analysis. Due to the negligible quantities of non-graphitic carbon in MWCNT, the present fitting procedure focuses on understanding phonon resonances to elucidate how varying modifications of MWCNT ultimately influence their graphitic bulk structure. We have found this approach to provide greater insight into the structure of MWCNT when low quantities of amorphous carbon are present, when compared with methods which try to interpret both phonon scattering and molecular vibrations simultaneously. Different pre-treatments for the modification of the graphitic structure of MWCNT are compared, including aqueous acidic and gas phase methods, and statistically evaluated. Focusing on phonon resonances enables one to analyze the reaction process of nitrosulfuric acid pre-treatment at different temperatures. Thereby, it is possible to control the ratio between defects and graphitic structures in MWCNT samples and prepare samples with reproducible D/G ratios