Today's graphene is normally produced using mechanical or thermal exfoliation, chemical vapour deposition (CVD), and epitaxial growth. One of the most effective way of synthesised graphene on a large scale could be by the chemical reduction of graphene oxide. Since the first report on mechanical exfoliation of monolayer graphene in 2004, interest in graphite oxide (which is produced by oxidation of graphite) has increased dramatically as people search for a cheaper, simpler, more efficient and better yielding method of producing graphene, that can be scaled up massively compared to current methods, and be financially suitable for industrial or commercial applications.
From Graphite Oxide to Graphene Oxide
While graphite is a 3 dimensional carbon based material made up of millions of layers of graphene, graphite oxide is a little different. By the oxidation of graphite using strong oxidizing agents, oxygenated functionalities are introduced in the graphite structure which not only expand the layer separation, but also makes the material hydrophilic (meaning that they can be dispersed in water). This property enables the graphite oxide to be exfoliated in water using sonication, ultimately producing single or few layer graphene, known as graphene oxide (GO). The main difference between graphite oxide and graphene oxide is, thus, the number of layers. While graphite oxide is a multilayer system in a graphene oxide dispersion a few layers flakes and monolayer flakes can be found.
Properties of Graphene Oxide
One of the advantages of the gaphene oxide is its easy dispersability in water and other organic solvents, as well as in different matrixes, due to the presence of the oxygen functionalities. This remains as a very important property when mixing the material with ceramic or polymer matrixes when trying to improve their electrical and mechanical properties.