Graphene oxide (GO) is a newly emergingmaterial of solutiondispersible polyaromatic, two-dimensional carbon sheets produced from acid exfoliation of graphite.18 It is like an insulating material with a wide bandgap, though its electronic structure depends on the stoichiometric carbon-to-oxygen atomic ratio. The basal plane of GO was covalently surrounded by the epoxide and hydroxyl groups, while edges were decorated with carboxyl functional groups.19 Due to the presence of several types of oxygen containing functional groups on the basal plane and
sheet edges the aromatic GO can undergo a complex interplay of covalent and noncovalent interactions with different molecules. GO based hybrids and composite materials with improved
properties have been synthesized with a range of organic and inorganic molecules via covalent, noncovalent and ionic interactions. 20 The oxygenated functional groups provide a 2Dnetwork
of sp2 and sp3 bonded atoms in GO,which leads to the presence of a finite bandgap depending on isolated sp2 domains.20 Tunability of the ratio of the sp2 and sp3 fractions by reduction chemistry can therefore controllably transform the insulating GO to a semiconductor and to a graphene-like semi-metal.21