Preparation and characterization of graphene oxide from coal

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 H 2 SO 4 in presence of NaNO 2 in an ultra-sonication system at 80 °C for 24 h followed by the addition of HNO 3 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 I D /I G 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. A facile method for the preparation of graphene oxide from bituminous coal through ultra-sonication has been reported and the product was characterized by various instrumentation techniques. • In this work, graphene oxide (GO) was synthesized from semi-bituminous coal by sonication. • Raw coal was demineralized to avoid the mineral matter content in the synthesized product. • SEM images of synthesized GO showed flaky morphology with distinct edges, wrinkled surfaces, stacked and layered structures. • The GO prepared from coal could be a low-cost precursor for bulk application in material science and technology.