A study of the correlation between the oxidation degree and thickness of graphene oxides

Thickness control is very important to commercial applications of 2D nanomaterials. The thickness of graphene oxide (GO) layers varies depending on the fabrication process, which is directly influenced by the content of oxygen functional groups. The correlation between the thickness and the degree of oxidation in different types of GO samples fabricated by various process are investigated through macroscopic and microscopic analysis. In this experiment, fabricated differently four GOs having various degree of oxidation were analyzed by X-ray Photoelectron Spectroscopy (XPS) to evaluate the degree of oxidation, respectively. A monolayer analysis by Atomic Force Microscope (AFM) and d-spacing analysis by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) were employed to compare and analyze the effect of the degree of oxidation on the thickness of the GO layers. The results showed that the degree of oxidation had a directly proportional relationship with the thickness and d-spacing of the specimens. Raman spectroscopy was also employed to further verify the proportional relationship between the degree of oxidation and the thickness of the GO specimens. The degree of oxidation of GO is to approximate by the analysis using the Raman spectroscopy, XRD and TEM results.