Synthesis and characterization of graphene oxide and graphene

Full text: Graphene has been widely studied due to its unique properties which are dependent on its structure then, the control of its synthesis is important. A modified Hummer 's method and thereafter reduction with aluminum in acidic media were used to obtain graphene oxide and graphene respectively, showing to be easy and reproducible. However, oxidation and reduction times and washing must be optimized to obtain pure materials with controlled properties. The characterization methods were X-ray diffraction (XRD) and X-ray photoelectron spectroscopy ( XPS ) with the facilities of the LDRX-UFF, the Soft X-ray Spectroscopy (SXS) beamline at the LNLS-Campinas (SXS-14393) and the XPS- RECAT-UFF. The x-ray diffraction can be roughly used as a fast method to monitor the synthesis with posterior more accurate XPS analysis. The graphene oxide samples analyzed in the XPS - LNLS showed C1s binding energies at 284.4- 285 eV, 286.5 eV and 287.9 according to C-C or C-H bond, C-OH and C = O, respectively. The graphite mineral used as a starting material presents a slightly oxidized surface, with a very intense band at approximately 284.4 eV and a little one at 285 eV . However, the C1s band for the reduced graphene oxide on the 287.9 e 286.5 eV region is diminished but not removed showing that the reduction is not complete. (author)