Abstract: Graphite oxide (GO) was prepared from liquid oxidation based on Hummers method and the graphene was then prepared using sodium borohydride to reduce the exfoliated graphite oxide by ultrasonication during which moderate sodium dodecyl benzene sulfonate (SDBS) was added into the suspension to reduce the agglomeration among the graphene layers and to obtain a stable graphene suspension. The as-prepared graphene was characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). XRD results show that the crystal structures are different among graphite, graphite oxide, and graphene. SEM and TEM images show that graphene possesses a gridding structure, a smooth surface, and few defects. AFM analysis indicates that the thickness of the single layer graphene is about 1.3 nm while there are still a few double layers in the sample. The BET specific surface area of the graphene was about 1206 m²·g^-1 and its H₂ adsorption properties were investigated under high pressure. The samples prepared by liquid oxidation-reduction were compared with that prepared by the improved liquid oxidation-reduction method, which indicates that the addition of SDBS effectively reduces agglomeration among the graphene layers and this generates high quality graphene. The adsorption capacities of H₂ on graphene at 25 and 55 °C reached 1.7%(w) and 1.1%(w), respectively, which are much higher than that reported previously.

Key words: Graphene, Graphite oxide, Hydrogen adsorption, Oxidation-reduction, Ultrasonic exfoliated