Synthesis of Reduced Graphene Oxide Using Novel Exfoliation Technique and its Characterizations

For processing of graphene based composite materials Graphene oxide is considered to be the main precursor. Though epitaxial growth and chemical vapor deposition techniques have been utilized to get monolayers of graphene, wet chemical process have been used for its large scale synthesis. For the extraction of graphene monolayer the chemical route relies on the weakening of the Van der Waals cohesive force upon the insertion of reactants in the inter layer space as a consequence sp2 lattice is partially degraded into a sp2-sp3 sheet that possesses a less π-π stacking stability. The method described here uses a novel chemical exfoliation technique. The graphite from the pencil lead is used as the precursor and it is treated with alcohol-ketone-surfactant mixture and mechanically and thermally agitated so as to get the golden brown colored suspension. The material was characterized by Fourier Transform Infra Red spectroscopy. The absence of 1570 cm – 1 peak clearly indicates the oxidation of C = C bonds. The SEM images confirmed the presence of the nanoplatelets of graphene oxide. The AFM analysis confirmed the sheet thickness of the graphene oxide sheets to be < 5 nm. The sheet resistance of the sheets of thermally treated graphene oxide or reduced graphene oxide on Si wafer (p-type, 4-6 Ω/cm) was measured as 200-300 Ω/□. The Ellipsometric characterisations also matches with that of the thermally reduced graphene oxide films formed.