Monitoring influence of chemical preparation procedure on the structure of graphene nanosheets

A comparison concerned about the three approaches (Hummers' method, improved method and Marcano–Tour's method, which all have been published and widely quoted in the field of producing graphene oxide) for the preparation of graphene oxide is discussed. The monitoring effect of preparation procedure is determined by investigating the influences of chemical reagents and reaction conditions on the structure of graphene nanosheets. The structure of graphene oxide and chemically reduced graphene is characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The exact mechanisms concerned about the effects of chemical reagents on the product structures are briefly described. The incorporation of H3PO4 and the addition of excessive H2SO4 and KMnO4 are proved to make a higher oxidation degree compared with the traditional methods. Ice in Marcano–Tour's method is also seen to be beneficial to the increase of the graphite oxide interlayer spacing. Surprisingly, the graphene, which is prepared by reducing the product of Marcano–Tour's method, shows less defects than the other two ones. In addition, the graphene oxide produced by improved method is found to confront with few difficulties during the reduction process.

► Additions of H3PO4, H2SO4 and KMnO4 make a high oxidation degree.
► Ice is beneficial to the increase of the GO interlayer spacing.
► R-IGO II shows less defects than the other two ones.
► GO II confronts with few difficulties during the reduction process.