36
O. Farinre et al.
One-unit cell structure of SnO 2
Top view
Overall view of
(110) plane
O
Sn
Fig. 7. Tetragonal rutile structure of SnO 2 showing the super cell of size (2 × 2 × 10) Å.
the van der Waals interaction, where C ij is the van der Waals constant and r ij is the
interatomic distance between i and j [13]. The coefficients of the Buckingham potential
are derived from Lewis and Catlow 1985 [16]. The rutile-like phase SnO 2 system is
developed as a 2 Å × 2 Å × 10 Å supercell, with a total of 480 particles (240 Sn and
240 O) and two types of bonds between Sn-O (i.e. 2.09, 2.08 Å), as shown in Fig. 8 [1].
The tin dioxide system is equilibrated by keeping the number of atoms, pressure, and
temperature constant by performing the NPT ensemble to obtain the lattice parameters
(i.e. a = b = 4.774690730 Å and c = 3.212953059 Å). The time of the run is 10 ns,
with time steps of 0.005 ps. The first principle calculation done by Lan et al. is in good
agreement with our results [6].
3.2 Graphene Nanoplatelets (GnPs)
The SEM images of pristine and functionalized GnPs are shown in Fig. 8 and they depict
how the platelet shaped GnPs are stacked randomly on each other forming aggregates.
For 35 wt% concentration of carboxyl in the GnPs, as compared to the 7 wt%, the SEM
images show that the platelets are tightly grouped to form conglomerates due to the
high number of oxygen-containing functional groups in the sample. Aggregates of GnP
samples are composed of platelets with diameters in the range 2.8–11.8 μ m, depending
on the number of platelets stacked in the aggregates, as shown in Table 3. The main
idea is to provide an approximate estimate of the lateral dimensions and thickness of the
aggregate particle size of pristine and functionalized GnPs.
The Raman spectra of pristine and functionalized GnPs are shown in Fig. 9, where
the D, G and 2D bands are observed, which confirms the Raman signature of graphene.
The G band is attributed to the in-plane vibration of the sp 2 bonded carbon atoms [17].
It also corresponds to the E 2g irreducible representation of longitudinal optical (LO) and
transverse optical (TO) phonon modes at the gamma () point of the Brillouin zone.
The D band indicates the degree of disorder in the sp 2 carbon lattice and corresponds to
the A 1g irreducible representation of the transverse optical (TO) phonon modes at the K
O. Farinre et al.
One-unit cell structure of SnO 2
Top view
Overall view of
(110) plane
O
Sn
Fig. 7. Tetragonal rutile structure of SnO 2 showing the super cell of size (2 × 2 × 10) Å.
the van der Waals interaction, where C ij is the van der Waals constant and r ij is the
interatomic distance between i and j [13]. The coefficients of the Buckingham potential
are derived from Lewis and Catlow 1985 [16]. The rutile-like phase SnO 2 system is
developed as a 2 Å × 2 Å × 10 Å supercell, with a total of 480 particles (240 Sn and
240 O) and two types of bonds between Sn-O (i.e. 2.09, 2.08 Å), as shown in Fig. 8 [1].
The tin dioxide system is equilibrated by keeping the number of atoms, pressure, and
temperature constant by performing the NPT ensemble to obtain the lattice parameters
(i.e. a = b = 4.774690730 Å and c = 3.212953059 Å). The time of the run is 10 ns,
with time steps of 0.005 ps. The first principle calculation done by Lan et al. is in good
agreement with our results [6].
3.2 Graphene Nanoplatelets (GnPs)
The SEM images of pristine and functionalized GnPs are shown in Fig. 8 and they depict
how the platelet shaped GnPs are stacked randomly on each other forming aggregates.
For 35 wt% concentration of carboxyl in the GnPs, as compared to the 7 wt%, the SEM
images show that the platelets are tightly grouped to form conglomerates due to the
high number of oxygen-containing functional groups in the sample. Aggregates of GnP
samples are composed of platelets with diameters in the range 2.8–11.8 μ m, depending
on the number of platelets stacked in the aggregates, as shown in Table 3. The main
idea is to provide an approximate estimate of the lateral dimensions and thickness of the
aggregate particle size of pristine and functionalized GnPs.
The Raman spectra of pristine and functionalized GnPs are shown in Fig. 9, where
the D, G and 2D bands are observed, which confirms the Raman signature of graphene.
The G band is attributed to the in-plane vibration of the sp 2 bonded carbon atoms [17].
It also corresponds to the E 2g irreducible representation of longitudinal optical (LO) and
transverse optical (TO) phonon modes at the gamma () point of the Brillouin zone.
The D band indicates the degree of disorder in the sp 2 carbon lattice and corresponds to
the A 1g irreducible representation of the transverse optical (TO) phonon modes at the K