Review of Chemical Vapor Deposition of Graphene and Related Applications
ABSTRACT Since its debut in 2004, graphene has attracted enormous interest because of its unique properties. Chemical vapor deposition (CVD) has emerged as an important method for the preparation and production of graphene for various applications since the method was first reported in 2008/2009. In this Account, we review graphene CVD on various metal substrates with an emphasis on Ni and Cu. In addition, we discuss important and representative applications of graphene formed by CVD, including as flexible transparent conductors for organic photovoltaic cells and in field effect transistors. Growth on polycrystalline Ni films leads to both monolayer and few-layer graphene with multiple layers because of the grain boundaries on Ni films. We can greatly increase the percentage of monolayer graphene by using single-crystalline Ni(111) substrates, which have smooth surface and no grain boundaries. Due to the extremely low solubility of carbon in Cu, Cu has emerged as an even better catalyst for the growth of monolayer graphene with a high percentage of single layers. The growth of graphene on Cu is a surface reaction. As a result, only one layer of graphene can form on a Cu surface, in contrast with Ni, where more than one layer can form through carbon segregation and precipitation. We also describe a method for transferring graphene sheets from the metal using polymethyl methacrylate (PMMA). CVD graphene has electronic properties that are potentially valuable in a number of applications. For example, few-layer graphene grown on Ni can function as flexible transparent conductive electrodes for organic photovoltaic cells. In addition, because we can synthesize large-grain graphene on Cu foil, such large-grain graphene has electronic properties suitable for use in field effect transistors.
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ABSTRACT: Gaseous gamma ray irradiation on graphene oxide.•Impact of the radicals formation on the surface functionalization.•Evaluation of morphological and crystallinity changes across the material.•New route to the formation of pre-assembled graphene oxide 3D architectures.Applied Surface Science 12/2014; 322:126-135. DOI:10.1016/j.apsusc.2014.10.070 · 2.54 Impact Factor
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ABSTRACT: We report on a highly efficient growth of graphene using dehydrogenation of acetylene by an oxidative reaction with carbon dioxide. In few seconds, large-area of copper foil used as catalyst of the reaction is fully covered with graphene. The yield of the reaction can be as high as 0.1%. This method allows the growth of multilayered graphene with misoriented layer stacking. This could be the result of functional (carboxylic, hydroxyl, epoxy) groups, taking the role of catalytic centers, attached to the surface of the layers. The thickness of graphene is controlled by the growth duration. The presence of the functional groups is useful for further chemical manipulations but they have limited impact on the electrical and optical properties of the graphene films. The as-synthesized bilayer graphene has a mobility of positive charge carriers of 2300 cm2 V−1 s−1 at room temperature. The high quality of the oxidative dehydrogenation product makes this process an attractive alternative to produce high quality graphene by chemical vapor deposition.Carbon 05/2014; 71:11–19. DOI:10.1016/j.carbon.2013.12.032 · 6.16 Impact Factor
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ABSTRACT: The stable dispersion of graphene flakes in aqueous medium is highly desirable for the development of materials based on this two-dimensional carbon structure, but current production protocols that make use of a number of surfactants typically suffer from limitations regarding graphene concentration or amount of surfactant required to colloidally stabilize the sheets. Here, we demonstrate that an innocuous and readily available derivative of vitamin B2, namely the sodium salt of flavin mononucleotide (FMNS), is a highly efficient dispersant in the preparation of aqueous dispersions of defect-free, few-layer graphene flakes. Most notably, graphene concentrations in water as high as ~50 mg mL-1 using low amounts of FMNS (FMNS/graphene mass ratios of about 0.04) could be attained, which facilitated the formation of free-standing graphene films displaying high electrical conductivity (~52000 S m-1) without the need of carrying out thermal annealing or other types of post-treatment. The excellent performance of FMNS as a graphene dispersant could be attributed to the combined effect of strong adsorption on the sheets through the isoalloxazine moiety of the molecule and efficient colloidal stabilization provided by its negatively charged phosphate group. The FMNS-stabilized graphene sheets could be decorated with nanoparticles of several noble metals (Ag, Pd and Pt), and the resulting hybrids exhibited a high catalytic activity in the reduction of nitroarenes and electroreduction of oxygen. Overall, the present results should expedite the processing and implementation of graphene in, e.g., conductive inks, composites and hybrid materials with practical utility in a wide range of applications.ACS Applied Materials & Interfaces 04/2015; 7(19). DOI:10.1021/acsami.5b00910 · 5.90 Impact Factor