Spectroscopic Characterization and Molecular Dynamics Simulation
37
Fig. 8. SEM images: (left) pristine GnPs; (middle) functionalized GnPs with 7wt% concentration
of carboxyl; and (right) functionalized GnPs with 35 wt% concentration of carboxyl.
Table 3. Average measurements along the x, y, z axes of aggregates of pristine and functionalized
graphene nanoplatelets (GnPs).
point of the Brillouin zone [18]. The 2D band on the other hand is the second order of the
D band and activated by two-phonon double resonance Raman scattering. In Fig. 9, the
D band intensities of the functionalized GnPs are observed to be higher than the D band
intensity of the pristine GnPs. In addition, the presence of a weak D’ peak is observed
in the Raman spectra of functionalized GnPs, which is activated by two-phonon double
resonance Raman scattering involving one LO phonon near the point [19].
We note that the D’ peak disappears when the percentage of carboxyl in the GnPs
is increased from 7 wt% to 35 wt% but reappears as a combination (D + D’) peak,
as shown in Fig. 10. Table 4 shows the calculated averages over five measurements of
the frequencies of the D, G, 2D peaks, and the relative intensities (I D /I G ) of the D and
G bands of pristine and functionalized GnPs. The values of I D /I G are used to verify
the successful functionalization of graphitic nanomaterials, as shown in Table 4. Earlier
research studies have shown that there is an indirect linear relationship between the inplane crystallite size (D a ) and I D /I G [20]. Thus, an increase in I D /I G of functionalized
37
Fig. 8. SEM images: (left) pristine GnPs; (middle) functionalized GnPs with 7wt% concentration
of carboxyl; and (right) functionalized GnPs with 35 wt% concentration of carboxyl.
Table 3. Average measurements along the x, y, z axes of aggregates of pristine and functionalized
graphene nanoplatelets (GnPs).
point of the Brillouin zone [18]. The 2D band on the other hand is the second order of the
D band and activated by two-phonon double resonance Raman scattering. In Fig. 9, the
D band intensities of the functionalized GnPs are observed to be higher than the D band
intensity of the pristine GnPs. In addition, the presence of a weak D’ peak is observed
in the Raman spectra of functionalized GnPs, which is activated by two-phonon double
resonance Raman scattering involving one LO phonon near the point [19].
We note that the D’ peak disappears when the percentage of carboxyl in the GnPs
is increased from 7 wt% to 35 wt% but reappears as a combination (D + D’) peak,
as shown in Fig. 10. Table 4 shows the calculated averages over five measurements of
the frequencies of the D, G, 2D peaks, and the relative intensities (I D /I G ) of the D and
G bands of pristine and functionalized GnPs. The values of I D /I G are used to verify
the successful functionalization of graphitic nanomaterials, as shown in Table 4. Earlier
research studies have shown that there is an indirect linear relationship between the inplane crystallite size (D a ) and I D /I G [20]. Thus, an increase in I D /I G of functionalized