Morphological/SAXS/WAXS studies on the electrochemical synthesis of graphene nanoplatelets

Abstract

Recently, graphene owing to its outstanding properties such as high mechanical strength, high thermal and electrical conductivity has been introduced as a surprising material for various applications. Up to now, the introduced methods mostly have some disadvantageous, especially in term of efficiency. Electrochemical exfoliation of graphite is a cost-effective, fast and environmentally friendly method for the synthesis of graphene nanoplatelets (GNPs). Based on this fact that the properties of GNPs are greatly depend on their morphology, the aim of this study was to evaluate the morphology of the obtained powders after electrochemical exfoliation of graphite by scanning electron microscopy. In this work, the mixture of H2SO4 + NaOH + H2O2 was used as the electrolyte. Effects of three concentrations of H2SO4 on the morphology of the obtained powders was examined. After determining the optimum sample, the analyses of transmission electron microscopy, X-ray diffraction, Raman spectroscopy and FTIR were used to characterize the produced GNPs by this method. Further characterization on the optimized sample was carried out by synchrotron small and wide angle X-ray scattering (SAXS/WAXS) to understand the shape and fractality of particles which have been confirmed to the initial results. Results indicated that based on electrolyte type and concentration of H2SO4, different kinds of carbon allotropes such as expanded graphite, multi-layered GNPs and few-layered GNPs can be obtained. Results showed the efficiency of the electrochemical method was increased with decreasing the concentration of the H2SO4; the few-layered GNPs were obtained using the lowest concentration of H2SO4.