Utilization of multiple graphene nanosheets in fuel cells: 2. The effect of oxidation process on the characteristics of graphene nanosheets

Structural properties of graphene nanosheets that will be used as electrode material in fuel cells were investigated at different oxidation times. As the oxidation time was increased, the strong bonding between graphene layers in graphite was reduced and graphene layers started to exfoliate forming clusters with a few number of graphene layers. The variations in interplanar spacings, layer number and percent crystallinity indicated how stepwise chemical procedure influenced the morphology of graphite. It was possible to produce relatively flat graphene clusters with definite number of layers by controlling the oxidation time. Graphene nanosheets were characterized in detail by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and thermal gravimetric analyzer. (C) 2011 Elsevier Ltd. All rights reserved.