Preparation and characterization of graphene oxide from coal

Abstract

Herein, we report a facile method for the preparation of graphene oxide from semi-bituminous coal. Ultrafine powdery (∼72 mesh) demineralized coal was treated with concentrated H2SO4 in presence of NaNO2 in an ultra-sonication system at 80 °C for 24 h followed by the addition of HNO3 to obtain the desired graphene oxide product. The synthesized material was characterized by Raman spectroscopy, XRD, XPS, FTIR, UV–vis spectroscopy, and Zeta potential analyzer. The Raman spectra of the synthesized product show two peaks at 1350 cm−1 and 1590 cm−1, corresponding to the D band and G band, respectively with an ID/IG value of about 1.04. C1s XPS data of synthesized material showed three peaks at 284.46 eV, 286.28 eV, and 289.35 eV corresponding to the presence of C-sp2 carbon, epoxide group, and carboxyl group respectively with the carbon percentage of 64% and the oxygen percentage of 26%. FTIR spectrum of the synthesized material showed a broad peak at 3428 cm−1 corresponding to the stretching mode of the O–H bond and a peak at 1626 cm−1 corresponding to the stretching and bending vibration of water molecules adsorbed on the material. SEM images of the synthesized material show distinct edges, wrinkled surfaces, stacked and layered structures compared to the coal. All the observed results indicate the formation of graphene oxide.