Spectroscopic Characterization and Molecular
Dynamics Simulation of Tin Dioxide, Pristine
and Functionalized Graphene Nanoplatelets
Olasunbo Farinre, Hawazin Alghamdi, and Prabhakar Misra (B)
Howard University, Washington, DC 20059, USA
pmisra@howard.edu
Abstract. Tin dioxide (SnO 2 ) is a semiconductor used in lithium batteries, solar
cells, as a photocatalyst, and for optronic device applications, due to its large direct
band gap, high electron mobility, thermal stability, large absorbance and storage
of light features, and cost-effectiveness. The present study concentrates on SnO 2
as a gas sensing material because of its enhanced selectivity for combustible and
toxic gases. Our spectroscopic investigation focuses on tetragonal rutile SnO 2 ,
aimed at studying its physical and chemical properties for gas sensors. We have
characterized SnO 2 using X-Ray diffraction (XRD) to confirm its tetragonal rutile
structure and calculate its crystallite size. Additionally, Raman spectroscopy with
a heated cell has been used to obtain the Raman active vibrational modes in the
temperature range 303.15–443.15 °K in order to study the anharmonic effects.
We have indeed observed a red shift in the Raman spectra for the A 1g and B 2g
vibrational bands, while the E g band exhibited no measurable change due to the
temperature increase. Furthermore, Scanning Electron Microscopy (SEM) has
been used to determine the surface morphology of SnO 2 and the 3-dimensional
view of an individual spherical grain. Graphene nanoplatelets (GnPs) have also
been investigated for toxic gas sensing applications due to their lightweight, large
surface area and low cost of fabrication. The presence of functional groups (e.g.
ammonia, fluorocarbon and carboxyl) in the nanoplatelets enhances the surface
interactions between the molecules being sensed (e.g. NO x and SO 2 ) and the
nanoplatelets themselves, thereby improving the sensing abilities of the GnPbased sensors. We have utilized SEM, Raman and XRD techniques for surface
and structural characterization of the pristine and functionalized GnPs. Our results
show that the major vibrational modes of graphene, namely the D, G and 2D peaks,
are observed in the Raman spectra of both pristine and functionalized GnPs. The
increase in the I D /I G values for functionalized GnPs reflects a smaller crystallite
size upon functionalization of the pristine GnPs, which is also supported by our
XRD results. A red shift in the frequency of the 2D peak is observed upon an
increase in carboxyl functionalization from 7 wt% to 35 wt% because the carboxyl
group behaves as an electron donor (n-type dopant) when attached to the edges
of the graphene lattice. In addition, we have utilized MD simulation using the
LAMMPS software code to study the vibrational properties of GnPs for better
understanding of its Raman properties suitable for the development of gas sensors.
O. Farinre and H. Alghamdi---These authors contributed equally to this work
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 29–43, 2021.
https://doi.org/10.1007/978-3-030-64690-5_4
Dynamics Simulation of Tin Dioxide, Pristine
and Functionalized Graphene Nanoplatelets
Olasunbo Farinre, Hawazin Alghamdi, and Prabhakar Misra (B)
Howard University, Washington, DC 20059, USA
pmisra@howard.edu
Abstract. Tin dioxide (SnO 2 ) is a semiconductor used in lithium batteries, solar
cells, as a photocatalyst, and for optronic device applications, due to its large direct
band gap, high electron mobility, thermal stability, large absorbance and storage
of light features, and cost-effectiveness. The present study concentrates on SnO 2
as a gas sensing material because of its enhanced selectivity for combustible and
toxic gases. Our spectroscopic investigation focuses on tetragonal rutile SnO 2 ,
aimed at studying its physical and chemical properties for gas sensors. We have
characterized SnO 2 using X-Ray diffraction (XRD) to confirm its tetragonal rutile
structure and calculate its crystallite size. Additionally, Raman spectroscopy with
a heated cell has been used to obtain the Raman active vibrational modes in the
temperature range 303.15–443.15 °K in order to study the anharmonic effects.
We have indeed observed a red shift in the Raman spectra for the A 1g and B 2g
vibrational bands, while the E g band exhibited no measurable change due to the
temperature increase. Furthermore, Scanning Electron Microscopy (SEM) has
been used to determine the surface morphology of SnO 2 and the 3-dimensional
view of an individual spherical grain. Graphene nanoplatelets (GnPs) have also
been investigated for toxic gas sensing applications due to their lightweight, large
surface area and low cost of fabrication. The presence of functional groups (e.g.
ammonia, fluorocarbon and carboxyl) in the nanoplatelets enhances the surface
interactions between the molecules being sensed (e.g. NO x and SO 2 ) and the
nanoplatelets themselves, thereby improving the sensing abilities of the GnPbased sensors. We have utilized SEM, Raman and XRD techniques for surface
and structural characterization of the pristine and functionalized GnPs. Our results
show that the major vibrational modes of graphene, namely the D, G and 2D peaks,
are observed in the Raman spectra of both pristine and functionalized GnPs. The
increase in the I D /I G values for functionalized GnPs reflects a smaller crystallite
size upon functionalization of the pristine GnPs, which is also supported by our
XRD results. A red shift in the frequency of the 2D peak is observed upon an
increase in carboxyl functionalization from 7 wt% to 35 wt% because the carboxyl
group behaves as an electron donor (n-type dopant) when attached to the edges
of the graphene lattice. In addition, we have utilized MD simulation using the
LAMMPS software code to study the vibrational properties of GnPs for better
understanding of its Raman properties suitable for the development of gas sensors.
O. Farinre and H. Alghamdi---These authors contributed equally to this work
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 29–43, 2021.
https://doi.org/10.1007/978-3-030-64690-5_4