Synthesis and Characterization of Carbon Nanomaterial from Indian Bituminous Coal

Abstract

Introduction: Carbon nanomaterials synthesis from low-cost precursors is a highly desirable approach for bulk application in material science and technology. Among the various nanomaterials, graphene-based carbon nanomaterials have attracted much attention in recent years. Graphene oxide (GO) is the oxygenated form of graphene. Oxygenated functionalities make the material hydrophilic and hence, the material can be dispersed in water and facilitated various types of functionalization through chemical modification to improve the material properties for wide applications. Coal is the most abundant combustible energy source. Although, coal possesses a very complex structure, however, it consists significant amount of polyaromatic structure. Due to the presence of an inherent polyaromatic structure (sp2-Carbon), coal becomes a promising candidate to replace graphite as a precursor material for the production of graphene /or graphene oxide. Methods: A facile cost-effective approach is reported to synthesize graphene oxide from semi-bituminous coal. Low-grade coal contains high mineral matter and thus, the demineralization process was employed to enrich the carbon matter by separating the mineral contents. Next, the demineralized coal was treated with H2SO4, NaNO2, and a little amount of concentrated HNO3 followed by washing and centrifugation to obtain the graphene oxide product. Results: The synthesized product was characterized by various instrumentation techniques and all the observed results indicate the formation of graphene oxide. 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. SEM analysis is evident that the synthesized product exhibits flake-like morphology with distinct edges, wrinkled surfaces, stacked and layered structures. XPS analysis confirms the formation of GO. Conclusion: The graphene oxide prepared from coal could be a low-cost precursor for bulk application in material science and technology.