Monolayer graphene from graphite oxide ☆ A. Dideykin a, ⁎, A.E. Aleksenskiy a , D. Kirilenko a,b , P. Brunkov a , V. Goncharov a , M. Baidakova a , D. Sakseev a , A. Ya.Vul' a a Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg, Russia b EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium abstract article info Available online 30 October 2010 Keywords: Graphene Graphite oxide Electron diffraction AFM SEM Graphene, a new carbon material, is attracting presently an increasing research interest. It stems from the unique electrical and mechanical properties of graphene predicted by theory. Experimental studies of graphene are, however, severely curtailed by a lack of an appropriate technique for its preparation. Mechanical cleavage of graphite proved to be ineffective, since it yields only very small (a few microns in size) particles of monolayer graphene. The rapidly developing approach based on chemical exfoliation of graphite produces large-area coatings composed primarily of arbitrarily oriented multilayer graphene particles. We have developed a technique for preparation of monolayer graphene sheets involving liquid exfoliation of crystalline graphite, which includes synthesis of graphite oxide by deep oxidation as an intermediate stage. Electron diffraction traces, as well as the variation of diffracted intensities with local orientation of graphene sheets, AFM, and HRTEM images testify to a remarkably good monolayer structure of the graphite oxide particles obtained by our technique. These results open a way to setting up high-efficiency production of monolayer graphene sheets appropriate for electrical and optical measurements and fabrication of structures for use in the field of applications. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Graphene is a truly remarkable nanocarbon material. Its unique structure and intriguing mechanical and electronic properties have made it a subject of an ever growing research interest all over the world. By definition, this material is a plane carbon layer with a thickness of one atom, which possesses a regular hexagonal structure accounted for by the sp 2 hybridization of orbitals of the atoms it is made of. Graphene is a practically perfect two-dimensional crystal with a conductivity mediated by electrons with zero effective mass. It is this feature that gives one grounds to consider graphene as a possible basis of solid- state electronics of the future [1]. Although theory has been studying the electronic properties of two-dimensional crystals for a long time already, the true surge of interest in graphene has been spawned by an experimental demonstration that it can exist in a free stable state. The high carrier mobility in graphene reaching 10 4 cm 2 /V s, which had been verified in the very first experiments, and observation of the room- temperature quantum Hall effect [2] have provided strong support for the basic theoretical concepts bearing on this material and paved the way to numerous studies of its properties and attempts at developing tentative structures of the corresponding electronic devices. The absence of an effective technology of fabrication of graphene is a serious obstacle holding down progress in experimental studies of graphene and graphene-based structures. Each of the methods employed presently in producing graphene films consisting of one or several graphene layers is plagued by severe limitations. Graphene films prepared on the surface of silicon carbide by an appropriate thermal treatment in vacuum or a neutral atmosphere cannot be separated from the substrate which mediates their electronic structure through interlayer coupling. Apart from this, the size of the uniform crystalline parts of such graphene films depends directly on the quality of the silicon carbide substrate surface and the accuracy with which it is oriented with respect to the basal crystal planes. Graphene film preparation on the surface of metals through segregation of the carbon dissolved in them or decomposition of vapors of hydrocarbons, a method enjoying presently considerable attention (it is by this approach that monolayer carbon films were originally obtained [3]), is also not free of fundamental limitations. In the first case, this method does not allow monitoring of the number of the deposited atomic layers, while in the second, it restricts the size of the graphene islands with a regular structure to that of crystallites on the metal surface. In both instances, analysis of the electronic properties of a de- posited film has to be preceded by peeling it off the metal surface. A group of methods aimed at preparation of graphene makes use of its remarkable feature, namely, that it reproduces exactly the structure of the atomic sheets making up crystalline graphite. Being coupled primarily by the weak van der Waals forces, these sheets can be Diamond & Related Materials 20 (2011) 105–108 ☆ Presented at NDNC 2010, the 4th International Conference on New Diamond and Nano Carbons, Suzhou, China. ⁎ Corresponding author. Tel.: + 7 812 2927917. E-mail address: dideikin@mail.ioffe.ru (A. Dideykin). 0925-9635/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2010.10.007 Contents lists available at ScienceDirect Diamond & Related Materials journal homepage: www.elsevier.com/locate/diamond