Surface modification of graphene by coupling with electron deficient radicals

In the present article, the surface modification of graphene by coupling with electron deficient nitroaryl radicals (NO2-Ar-center dot) under microwave irradiation was reported. The NO2-Ar-center dot species were generated insitu by reaction of nitroaniline derivatives with isoamyl nitrite as a diazotization agent, followed by decomposition of nitroaryl diazonium intermediates. The nitrogen-rich graphene flakes prepared by this procedure were characterized by energy dispersive X-ray (EDX) and elemental map. The morphology of graphene before and after surface modification was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman and Fourier transform infrared (FT-IR) spectroscopy. Additionally, density functional theory (DFT) calculations were carried out to investigate the optimized geometry, structural parameters, molecular orbitals, density of states (DOS), Raman, infrared (IR) and carbon-13 nuclear magnetic resonance (C-13 NMR) of graphene modified by a variety of NO2-Ar-center dot species. Energy decomposition analysis (EDA) was performed for evaluating the contribution of dispersion, polarization, electrostatic and exchange energies to the interaction energy of nitroaryl radicals with graphene. Results showed that the surface modification of graphene by coupling with nitroaryl radicals leads to the significant changes in the morphological, structural, electronic, conductive and spectral properties of graphene. Moreover, the bonding nature between nitroaryl radicals and graphene is covalent.