Progress in the Raman spectra analysis of covalently functionalized multiwalled carbon nanotubes: unraveling disorder in graphitic materials

Abstract

Raman spectroscopy is highly sensitive to the morphology and electronic structures of graphitic materials, but a convenient interpretation model has been lacking for multiwalled carbon nanotubes (MWCNTs), in particular for the discrimination of spectral changes induced by covalent functionalization. The present work describes a systematic investigation of the Raman analysis of covalently functionalized MWCNTs by diazonium chemistry and oxidation methodologies, with typically different mechanisms and reaction sites. A multi-peak deconvolution system and spectral band assignment were proposed based on the chemical and structural modifications identified by X-ray photoelectron spectroscopy, thermogravimetry, X-ray diffraction, specific surface areas and the comparative analysis of the first and second order regions of the Raman spectra. Diazonium functionalization takes place mainly in the π-system of the external sidewall, while oxidation occurs on defects and leads to structure burning. This allowed us to distinguish between spectral features related to aromaticity disruptions within the sidewalls and spectral features related to changes within the inner tubes. The model was validated extending the studies to the functionalization of MWCNTs by the Bingel reaction.

Highly Efficient Porous Carbon Electrocatalyst with Controllable N‐Species Content for Selective CO2 Reduction

“…The similar XRD patterns between NPC‐1000 and PC‐1000, which was prepared from Zn‐MOF‐74 with the absence of melamine, indicate that the presence of melamine does not influence the crystalline structure of the derived carbon (Figure a). Raman spectra of NPC‐1000 and PC‐1000 show two distinct features at 1365 and 1586 cm −1 , which correspond to the D and G bands, respectively (Figure b) . The intensity ratio of D band to G band for NPC‐1000 is 1.16, which is higher than that of PC‐1000 (0.86).…”

Multiwalled carbon nanotube-supported CuCo2S4 as a heterogeneous Fenton-like catalyst with enhanced performance

“…2 shows the nitrogen adsorption/desorption isotherms of CuCo 2 S 4 and CuCo 2 S 4 /MWCNTs, and the nitrogen adsorption/ desorption isotherms of MWCNTs are shown in Fig. S6 29 The relative areas of satellite bands (S, Dl, Dr, Gl and Gr bands) and those of graphitic-type domain bands (D and G bands) are summed respectively and their ratio is used to reect the chemical functionalization degree. The ratio for MWCNTs was 0.5, while for CuCo 2 S 4 /MWCNTs it was 0.7.…”

Sulfur‐Containing Molecules Grafted on Carbon Nanotubes as Highly Cyclable Cathodes for Lithium/Organic Batteries

“…Here, the I D / I G ratios are close to 1.30 in both cases and one can only observe a small decrease of intensity of the 2D band upon functionalization. This counter intuitive behavior is however classical in the case of functionalization of MWNTs …”