A study of graphenes prepared by different methods: characterization, properties and solubilization

Abstract

Graphene has been prepared by different methods: pyrolysis of camphor under reducing conditions (CG), exfoliation of graphitic oxide (EG), conversion of nanodiamond (DG) and arc evaporation of SiC (SG). The samples were examined by X-ray diffraction (XRD), transmission electron microscopy, atomic force microscopy, Raman spectroscopy and magnetic measurements. Raman spectroscopy shows EG and DG to exhibit smaller in-plane crystallite sizes, but in combination with XRD results EG comes out to be better. The CG, EG and DG samples prepared by us have BET surface areas of 46, 925 and 520 m² g⁻¹ respectively and exhibit significant hydrogen uptake up to 3 wt%. EG also exhibits a high CO₂ uptake (34.7 wt%). Electrochemical redox properties of the graphene samples have been examined in addition to their use in electrochemical supercapacitors. Functionalization of EG and DG through amidation has been carried out with the purpose of solubilizing them in non-polar solvents. Water-soluble graphene has been produced by extensive acid treatment of EG or treatment with polyethylene glycol.