An improved method for the preparation of graphene oxide (GO) is described. Currently, Hummers’ method (KMnO4, NaNO3, H2SO4) is the most common method used for preparing graphene oxide. We have found that excluding the NaNO3, increasing the amount of KMnO4, and performing the reaction in a 9:1 mixture of H2SO4/H3PO4 improves the efficiency of the oxidation process. This improved method provides a greater amount of hydrophilic oxidized graphene material as compared to Hummers’ method or Hummers’ method with additional KMnO4. Moreover, even though the GO produced by our method is more oxidized than that prepared by Hummers’ method, when both are reduced in the same chamber with hydrazine, chemically converted graphene (CCG) produced from this new method is equivalent in its electrical conductivity. In contrast to Hummers’ method, the new method does not generate toxic gas and the temperature is easily controlled. This improved synthesis of GO may be important for large-scale production of GO as well as the ...

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Improved Synthesis of Graphene Oxide

Approaches, Derivatives and Applications Vasilios Georgakilas,† Michal Otyepka,‡ Athanasios B. Bourlinos,‡ Vimlesh Chandra, Namdong Kim, K. Christian Kemp, Pavel Hobza,‡,§,⊥ Radek Zboril,*,‡ and Kwang S. Kim* †Institute of Materials Science, NCSR “Demokritos”, Ag. Paraskevi Attikis, 15310 Athens, Greece ‡Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University Olomouc, 17. listopadu 12, 771 46 Olomouc, Czech Republic Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo naḿ. 2, 166 10 Prague 6, Czech Republic

Functionalization of Graphene: Covalent and Non-Covalent Approaches, Derivatives and Applications

Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

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Graphene-based composites

Graphene based materials: Past, present and future

Graphene oxide: preparation, functionalization, and electrochemical applications.

In this study, we report an inexpensive, massively scalable, fast, and facile method for preparation of graphene oxide and reduced graphene oxide nanoplatelets. The basic strategy involved the preparation of graphite oxide (GO) from graphite through reaction with benzoyl peroxide (BPO), complete exfoliation of GO into graphene oxide sheets, followed by their in situ reduction to reduced graphene oxide nanoplatelets. The mechanism of graphene oxide producing is mainly the generation of oxygen-containing groups on graphene sheets. In addition, inserted BPO and expansion of CO2 evolved during reaction will expand the distance between graphite layers, which are also main factors for exfoliation. Thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy indicated the successful preparation of GO. X-ray diffraction proved the mechanism of intercalation and exfoliation of graphite. Transmission electron microscopy and atomic force microscopy were used to demonstrate the structur...

Fast and Facile Preparation of Graphene Oxide and Reduced Graphene Oxide Nanoplatelets

An in situ chemical synthesis approach has been employed to prepare an Ag-chemically converted graphene (CCG) nanocomposite. The reduction of graphene oxide sheets was accompanied by generation of Ag nanoparticles. The structure and composition of the nanocomposites were confirmed by means of transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray diffraction. TEM and AFM results suggest a homogeneous distribution of Ag nanoparticles (5–10 nm in size) on CCG sheets. The intensities of the Raman signals of CCG in such nanocomposites are greatly increased by the attached silver nanoparticles, i.e., there is surface-enhanced Raman scattering activity. In addition, it was found that the antibacterial activity of free Ag nanoparticles is retained in the nanocomposites, which suggests they can be used as graphene-based biomaterials.

/pdf/facile-synthesis-and-application-of-ag-chemically-converted-5dsj8xh5ym.pdf

Facile synthesis and application of Ag-chemically converted graphene nanocomposite

Graphene, a flat monolayer of carbon atoms tightly packed into a two-dimensional honeycomb lattice, has attracted a great deal of attention in recent years for potential applications in many technological fields, such as nanoelectronics, nanocomposites, and hydrogen supercapacitors. One possible route to harnessing these properties would be to incorporate graphene sheets into composite materials. The manufacturing of such composites requires not only that the graphene sheets are produced on a sufficient scale, but also that they are incorporated, and homogeneously distributed, into various matrices. Graphite, which consists of a stack of flat graphene sheets, is available in large quantities from natural sources. It is likely the most readily available and least expensive source for the production of bulk graphene sheets. Graphite oxide (GO) is a layered material produced by the oxidation of graphite. In contrast to pristine graphite, the graphene-derived sheets in GO are heavily oxygenated and bear hydroxyl and epoxide functional groups on their basal planes, in addition to carbonyl and carboxyl groups located at the sheet edges. Unfortunately, owing to their hydrophilic nature, graphene oxide sheets can only be dispersed in aqueous media that are incompatible with most organic solvents and polymers. In addition, GO is electrically insulating, which limits its usefulness for the synthesis of composites. However, it has been demonstrated that the electrical conductivity of GO can be significantly increased and very thin graphene-like sheets can be obtained through the chemical reduction of exfoliated GO. Just like carbon nanotubes, a key challenge in the synthesis and processing of bulk-quantity graphene sheets is aggregation. Graphene sheets, due to their high specific surface area, tend to form irreversible agglomerates or even restack to form graphite through van der Waals interactions. As with carbon nanotubes, full utilization of graphene sheets in polymer nanocomposite applications will inevitably depend on their ability to achieve complete dispersion in the polymer matrix of choice.

Synthesis of amphiphilic graphene nanoplatelets.

In this study, graphene oxide−magnetic nanoparticle composites were prepared by attaching magnetic nanoparticles to graphene oxide through a high temperature reaction of ferric triacetylacetonate with graphene oxide in 1-methyl-2-pyrrolidone. X-ray diffraction, transmission electron morphology, and thermogravimetric analysis were used to demonstrate the successful attachment of iron oxide nanoparticles to graphene sheets. It was found that the attached nanoparticles were mainly magnetite. Investigations using Fourier transform infrared spectroscopy proved that the tight attachment was due to the robust linkage: metal−carbonyl coordination.

Yizhe Hu

Papers

Fast and Facile Preparation of Graphene Oxide and Reduced Graphene Oxide Nanoplatelets

Facile synthesis and application of Ag-chemically converted graphene nanocomposite

Synthesis of amphiphilic graphene nanoplatelets.

One Step Synthesis of Graphene Oxide−Magnetic Nanoparticle Composite

The reinforcement role of different amino-functionalized multi-walled carbon nanotubes in epoxy nanocomposites