Spectroscopic Characterization and Molecular Dynamics Simulation of Pristine and Functionalized Graphene nanoplatelets (GnPs)

The present study focuses on investigating Graphene nanoplatelets (GnPs) for toxic gas sensing applications due to their large surface area and low cost of fabrication. We have used Raman, SEM, FTIR and XRD techniques for structural and spectroscopic characterization of pristine and functionalized GnPs (with carboxyl). The major vibrational modes of graphene: D, G and 2D peaks appear in the Raman spectra of pristine and functionalized GnPs. A red-shift in the frequency of the 2D peak observed in the Raman spectra of GnPs functionalized with 35 wt.% carboxyl group is indicative of an electron donor when carboxyl is attached to the layer edges. XRD spectra show that an increase in the FWHM of the GnPs reflect a smaller crystallite size ranging from 3.5-16 nm. In addition, we performed MD simulation on trilayer graphene to compare with our experimental data based on the 3-6 layers of graphene present in the individual platelet sheets. Our calculated D, G and 2D peaks from the MD simulation were found to be: 1331 cm^-1, 1581 cm^-1 and 2662 cm^-1, respectively, which agree well with our Raman results. These results are promising and show that GnPs are suitable candidates for applications in highly sensitive and selective toxic gas sensors.