Understanding of Coal Chemistry and Synthesis of Carbon Nano-Materials

Since the time of its discovery in 2004, graphene has attracted researchers in the field of nanotechnology because of tremendous and wide range applications[1][2][3]. However, its mass production was restricted to graphite as a starting material. To offset the high cost of graphite, coal, being inexpensive, abundant in nature and with major content carbon is the best choice to replace graphite in addition to being used as source of energy. In this work, we discuss (i) the molecular structure of coal and thermally treated coal via spectroscopic and electrical characterizations, (ii) the chemistry of exfoliating graphene from coal. In the beginning, few and discontinuous areas of graphene oxide were produced following modified Hummer’s method, after characterized for the inelastic vibrations of sp2 bonded carbons. The defect induced A1g (D band) mode with Raman shift of 1352 cm-1 and the E2g (G band) in-plane vibrations of carbon atoms at 1596 cm-1 for raw coal and 1377 cm-1 (D band) and 1592 cm-1 (G band) for thermally treated coal were observed. The D to G peak intensity ratios (ID/IG) for raw coal and thermally treated coal were 1.004 and 0.95 respectively. In order to achieve highly uniform and continuous surface of graphene oxide and to avoid the damage of the aromatic portion of coal by the high oxidizing agent (KMnO4), we developed a use of low oxidizing agent (NaNO2) since coal has incompact structure and requires partial oxidation to exfoliate its crystalline portion. We can find a larger area of graphene oxide coverage with D band at 1352 cm-1 and G band at 1584 cm-1 and ID/IG of 0.99.