Optimization study of graphene oxide synthesis with improvement of C/O ratio

Abstract

The present study was aimed to clarify detailed conditions of vigorous solid-state reaction as conventional method for graphene oxide. For optimization study, the effects of an initial concentration of KMnO4 (0.75-7.5 % w/v), reaction temperature (0-120 °C) and an incubation time (1-48 h) were investigated. The obtained graphene oxide was characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy and scanning electron microscope (SEM) techniques. From the results, the optimum conditions for graphene oxide production were consisted of 4.5 % w/v KMnO4 at 80 °C for 6 h. IR spectrum showed the characteristic peaks at wave number (cm-1) of 3367 (O-H), 1719 (C=O), 1224 and 1049 (C-O). Energy dispersive X-ray spectroscopy of the graphene oxide revealed the improved C/O ratio of 1.10, indicating more polar functional groups bound on the surface of graphene oxide due to the increasing oxidation by MnO 4 -. The amorphous graphene oxide was obtained as confirmed by XRD pattern. Additionally, SEM image showed drastically differences in the surfaces between graphene oxide and its graphite powder, depicting a graphene oxide's smooth surface compared with that rough multilayer graphite powder. It could, thus, be gained a crucial factor affecting the graphene oxide synthesis from graphite powder under the optimized method.