7. Physical properties and Raman spectra of graphene Nanoplatelets

All of the graphene nanoplatelet samples investigated in the current study (functionalized oxygen, nitrogen, argon, ammonia, carboxyl and fluorocarbon) have similar shapes (see Table 2 and Figure 19) [17]. Graphene nanoplatelet aggregates (aggregates of sub-micron platelets with diameters of <2 microns and a thickness of a few nanometers) were identified and studied, rather than individual nanoplatelets (STREM Data Sheets) [18].

graphene, the Raman spectra are characterized by the G and 2D bands. The D band present in the spectra signaled some defects. The behavior of the sharp Lorentzian G-band, at 1587 cm<sup>1</sup>

Figure 20. Offset Raman measurements of CVD graphene (a), functionalized graphene nanoplatelet aggregates doped with ammonia (b), argon (c), carboxyl (d), fluorocarbon (e), nitrogen (f), and oxygen (g) at room temperature (~25C)

Figure 19. 3D view of SEM data of functionalized graphene nanoplatelet aggregates doped with argon (a), carboxyl (b),

Raman Spectroscopy of Graphitic Nanomaterials http://dx.doi.org/10.5772/intechopen.72769 175

oxygen (c), ammonia (d), fluorocarbon (e), and nitrogen (f) via Gwyddion software [19].

can also be used to verify the sample layer thickness. An increase in the number of layers lowers the frequency of this band, along with an increase in peak intensity. The 2D band, however, depends on the band position and shape, exhibiting distinct band shape differences with the numbers of layers present (AZO Materials) [20]. Figure 20 indicates identical position and shape of G and 2D bands visible in the spectra of the CVD graphene and the func-

The thermal characteristics of a variety of graphitic nanomaterials (single-walled and multi-walled carbon nanotubes, graphene and functionalized graphene in the form of nanoplatelets) have been investigated in the temperature range 24.0–200C using Raman spectroscopy for enhanced gas-sensing and optoelectronic applications. A Kataura plot analysis has been presented for the Radial Breathing Mode vibrations of single-walled carbon nanotubes and possible chiralities identified that pertain to metallic, semiconductor and type 2 semiconducting SWNTs. The effect

tionalized graphene nanoplatelet samples at room temperature (~25C).

8. Conclusions and outlook

displayed using the Renishaw's WiRE software [21].

,

The electronic structure of graphitic nanocarbons is linked to its structure, and Raman spectroscopy is sensitive to this intimate and unique relationship, which makes it very effective at studying the various functionalized graphene nanoplatelets used in this study. Akin to pristine


Table 2. Average x, y, z axis spatial measurements of functionalized graphene nanoplatelet aggregates.

Figure 19. 3D view of SEM data of functionalized graphene nanoplatelet aggregates doped with argon (a), carboxyl (b), oxygen (c), ammonia (d), fluorocarbon (e), and nitrogen (f) via Gwyddion software [19].

Figure 20. Offset Raman measurements of CVD graphene (a), functionalized graphene nanoplatelet aggregates doped with ammonia (b), argon (c), carboxyl (d), fluorocarbon (e), nitrogen (f), and oxygen (g) at room temperature (~25C) displayed using the Renishaw's WiRE software [21].

graphene, the Raman spectra are characterized by the G and 2D bands. The D band present in the spectra signaled some defects. The behavior of the sharp Lorentzian G-band, at 1587 cm<sup>1</sup> , can also be used to verify the sample layer thickness. An increase in the number of layers lowers the frequency of this band, along with an increase in peak intensity. The 2D band, however, depends on the band position and shape, exhibiting distinct band shape differences with the numbers of layers present (AZO Materials) [20]. Figure 20 indicates identical position and shape of G and 2D bands visible in the spectra of the CVD graphene and the functionalized graphene nanoplatelet samples at room temperature (~25C).
