Graphene with high purity

Graphene is a two-dimensional form of crystalline carbon, either a single layer of carbon atoms forming a hexagonal lattice or several coupled layers of this honeycomb structure. In many respects, two-dimensional systems are fundamentally different from three-dimensional systems. In particular, due to very strong thermal fluctuations of atomic positions that remain correlated at large distances, long-range crystalline order cannot exist in two dimensions. Instead, only short-range order exists, and it does so only on some finite scale of characteristic length, a caveat that should be noted when graphene is called a two-dimensional crystal. For this reason, two-dimensional systems are inherently flexural, manifesting strong bending fluctuations, so that they cannot be flat and are always rippled or corrugated. Graphene, because of its relative simplicity, can be considered as a model system for studying two-dimensional physics and chemistry in general. Other two-dimensional crystals besides graphene can be derived by exfoliation from other multilayer crystals or by chemical modification of graphene. Modern electronics are basically two-dimensional in that they use mainly the surface of semiconducting materials. Therefore, graphene and other two-dimensional materials are considered very promising for many such applications. Using graphene, for example, it should be possible to make transistors and other electronic devices that are much thinner than devices made of traditional materials. Graphene also has very high thermal conductivity and, therefore, could be used to remove heat from electronic circuits. The field of graphene science and technology is relatively new. In the decades that followed, it remained difficult to say which applications would prove to be the most popular. Progress depends not only on the basic science but also on the development of new ways to produce graphene on an industrial scale. Obtaining graphene by exfoliation is too expensive for mass production. Methods proposed include the formation of graphene layers by burning silicon carbide or by chemical vapor deposition of carbon on the surface of some metals such as copper or nickel. These methods would allow the production of samples of graphene that were macroscopically large in two dimensions but still atomically thin. Contributor: Junjie Chen, ORCID: 0000-0001-5055-4309, E-mail address: [e-mail], Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China