The effect of thermal and ultrasonic treatment on the formation of graphene-oxide nanosheets

Thermal and ultrasonic treatments of graphene oxide (GO) are proposed to produce grapheneoxide layers. These layers were comprehensively characterized by using 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 the GO layers produced by using thermal treatment showed a broad peak at around 26.09 .deg. , and those of the GO layers produced by using ultrasonic treatment showed a distinct peak at 11.07 .deg. . The FT-IR spectra indicated that the ultrasonic treatments for the sample GO did not change the functional group; however, all oxygen containing functional groups in the GO layers produced by using thermal treatment were nearly completely removed. The EDX results showed that only 8.6 wt.% oxygen still existed in the sample of GO layers produced by using 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, the clear G peak and the characterized 2D band in the Raman spectra indicate the existence of defect-free monolayer and few-layer graphenes. AFM results showed that a single layer of thermally treated graphene oxide had been produced.