Synthesis of multilayer graphene and its graphene derivatives from coal

Abstract

In our study, we selected three prevalent coal types from Xinjiang: Dahuangshan coal (referred to as Y-coal), Black Mountain coal (B-coal), and Kuche coal (K-coal). Initially, we assessed their morphological differences using electron microscopy. Subsequently, we evaluated the superiority of Y-coal through Thermogravimetric Analysis (TGA). Furthermore, we compared their performances using various electrochemical tests, including the J-V curve, dark current curve, open-circuit voltage curve, and Electrochemical Impedance Spectroscopy (EIS) curve. Ultimately, we investigated the potential of synthesizing graphene from Y-coal and its derivatives. The first step was the preparation of multilayer graphene (MG) by treating Y-coal with acid to obtain demineralized coal, followed by treatment in a tube furnace to obtain ultrafine powdered MG. The second step was then followed by successive oxidation and ultrasonication of the already obtained MG to obtain graphene oxide (GO). Finally, ascorbic acid (VC) was selected to treat GO to prepare an aqueous suspension of reduced graphene oxide (rGO). MG (2θ = 26.2°), GO (2θ = 12.4°) and rGO (2θ = 25.5°) were obtained by XRD analysis. C 1s and O 1S were analyzed by XPS spectra. The functional groups −OH, C=O, and −C=C–, which are unique to graphene and its derivatives, were comparatively analyzed using infrared spectroscopy. The change of π→π* was analyzed by the UV–vis method. The absorbance was further found in combination with PL spectra. Immediately after, the morphology of graphite and its derivatives was analyzed by SEM, HRTEM, the physical properties by contact angle and BET, and finally the content of elements C and O by EDS. The successful demonstration of the superiority of the synthesized MG and its derivatives was achieved.