Graphenes essentially are individual carbon layers of graphite. In today's technical usage, however, the term “graphene” refers primarily to grades consisting of multiple carbon layers. Although graphene represents the simplest form of nanocarbon, its existence was first proven in 2004 by Geim and Novoselov. Both were awarded the 2010 Nobel Prize in Physics for their discovery.
Today, graphenes are largely manufactured using catalytic processes or by reduction of graphite oxide, which is easily prepared from regular graphite by oxidation. Depending on which process was used to manufacture the graphene, it will carry a greater or lesser number of functional groups. Special processes can be used to produce graphene layers directly on planar surfaces, after which they can be transferred to other surfaces as an important building block in optoelectronic applications. Here, graphitic carbons constitute carbon compounds that are based on the structure of graphene or graphite. They form a three-dimensional, hexagonal, crystalline long-range order in the material, which can be demonstrated using diffraction methods. Along with graphene and graphite oxide, soot and activated carbon also belong to the group of graphitic carbons. Of the known carbon allotropes, graphenes are the youngest product on the market. Especially if they have very few layers, they are therefore somewhat more expensive than other nanocarbon materials and are not yet commercially available in large volumes. Many potential applications remain under development, but the first products are already available.