Investigation of the effects of temperature and time on reduction of graphene oxide by microwave hydrothermal reactor

Graphene oxide (GO) sheets were synthesized by modified Hummers method. Microwave hydrothermal reactor (MHR) was applied to reduce graphene oxide. Different temperatures 50 and 180°C were applied to fabricate four samples with 4, 10, 25 and 60 min exposure times. The deoxygenation of the GO sheets after exposure to MHR was revealed by using UV–visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Raman spectroscopy. Based on XPS analysis, the O/C ratio of the GO sheets decreased from 49 to 17% after exposure to MHR. On the other hand, characterization by TGA illustrated that the O/C ratio of the GO dramatically decreases after exposure of MHR and reached from 37 to 7%. Raman spectroscopy demonstrated that there was no increase in defects’ density after reduction. The results confirmed that sample with 180°C exposure temperature and 60 min exposure time was reduced completely. Therefore this can help to advance using MHR as the green technique of GO reduction.