Sintesis Del Grafeno

PERSPECTIVE pubs.acs.org/JPCL

Graphene Chemistry: Synthesis and Manipulation
Zhengzong Sun, Dustin K. James, and James M. Tour*
Richard E. Smalley Institute for Nanoscale Science and Technology, Department of Chemistry and Department of Mechanical Engineering and Materials Science, Rice University, 6100 Main Street, Houston, Texas 77005, United States ABSTRACT: Monolayer graphene is atwo-dimensional material with fascinating electrical and optical properties that has brought great possibilities and challenges to chemists. The possibilities include the many applications in which graphene could be exploited, and the challenges involve optimizing synthetic strategies and manipulating the structure and properties so that graphene can be used in those applications. Here, we cover aportion of the recent progress toward using chemical techniques to render graphene available for incorporation into electronic and optical devices. With top-down and bottom-up strategies, the geometry and thickness of graphene have been well-tuned. The methods for producing structure-doped materials, such as nitrogen doping and h-BNC hybrid structures, are discussed along with the properties of thosedoped materials. Finally, covalent functionalization of graphene’s surfaces and edges, such as hydrogenation and the diazonium and azide reactions, will be discussed as they have become powerful tools to modify the properties of graphene.

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raphene can be viewed as less than 10 layers of graphite.1 Hence, monolayer graphene is a single-atom-thick sheet of sp2 carbon atoms, while bilayergraphene is two sheets. Because graphene has a structure analogous to benzene and polycyclic aromatic hydrocarbons (PAHs), the chemistries of the compounds can be thought to be similar. Breaking and formation of conjugated sp2 CÀC bonds (basal plane) or sp2 CÀH bonds (edge) are important in this chemistry. To synthesize graphene, various forms of carbon are transformed into the monolayer hexagonalsymmetrical conjugated sp2 structure. To chemically modify graphene, these sp2 bonds are broken, and new bonds are made to exogenic functional groups. However, modification of the flat, rigid structure of graphene is challenging because of the necessity for overcoming the high-energy barriers associated with intralayer conjugation and interlayer van der Waals forces, thereby usually requiring hightemperature or energetic species

Graphene has a structure analogous to benzene and polycyclic aromatic hydrocarbons (PAHs); the chemistries of the compounds can be thought to be similar. Breaking and formation of conjugated sp2 CÀC bonds (basal plane) or sp2 CÀH bonds (edge) are important in this chemistry.
r 2011 American Chemical Society

to complete the reactions. Under moderate reactionconditions, the yields of the reactions are usually low. For such reasons, new synthetic procedures are needed to optimize graphene’s structures and to manipulate its properties. In this Perspective, we will focus on graphene chemistry that is targeted to produce specific sizes, geometries, band gaps, doping levels, and/or functionalized addends, all modifications that could be applied to the productionof graphene-based electronic and optical devices. Other applications, such as chemistry to produce graphene-based composite materials and graphenebased nanomedicine products, will not be covered in detail in this paper. Synthesis of Graphene of a Particular Geometry. Generally, a material’s electrical and optical properties are closely related to its size and dimensions. This is particularlyreflected in the dimension control of graphene, both vertically and laterally (Figure 1). Zero band gap semimetal graphene was first discovered by mechanically reducing the thickness from 3D bulk graphite to a 2D single layer sheet.2 Soon after this, researchers found that graphene’s band gap could be opened through gating bilayer graphene or shrinking its lateral size to sub-10 nm narrow ribbons.3,4...