Thermal and ultrasonic treatments of graphene oxide (GO) are proposed to produce the graphene oxide layers. These layers were comprehensively characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy and Atomic Force Microscopy (AFM). The XRD patterns of GO layers by thermal treatment showed a broad peak at around 26.09??and GO layers by ultrasonic treatment showed a distinct peak at 11.07?? The spectra of FT-IR indicated that the ultrasonic treatments for the sample GO had not changed the functional groups, however all oxygen-containing functional groups in GO layers by thermal treatment were nearly completely removed. The EDX results showed that only 8.6 wt.% oxygen were still existed in the sample of GO layers by thermal treatment. From the TEM images, monolayer graphene oxide could be found in a flake form in the GO layers by thermal treatment. The visible D peak, clear G peak and characterized 2D band in the Raman spectra indicated the existence of defect-free monolayer and few-layer graphenes. AFM results showed that the single layer of thermal treatment of graphene oxide has been produced.

Keywords: Graphene oxide, thermal and ultrasonic treatment, TEM, Raman, AFM