The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

/pdf/the-chemistry-of-graphene-oxide-507zcedhhu.pdf

The chemistry of graphene oxide

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 ...

https://www.researchgate.net/file.PostFileLoader.html?id=54ca19b4cf57d79a768b4618&assetKey=AS%3A273691751976961%401442264606356

Improved Synthesis of Graphene Oxide

Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.

http://science.sciencemag.org/content/sci/297/5582/787.full.pdf

Carbon Nanotubes--the Route Toward Applications

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

/pdf/graphene-and-graphene-oxide-synthesis-properties-and-2q80uaujok.pdf

Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Graphene sheets offer extraordinary electronic, thermal and mechanical properties and are expected to find a variety of applications. A prerequisite for exploiting most proposed applications for graphene is the availability of processable graphene sheets in large quantities. The direct dispersion of hydrophobic graphite or graphene sheets in water without the assistance of dispersing agents has generally been considered to be an insurmountable challenge. Here we report that chemically converted graphene sheets obtained from graphite can readily form stable aqueous colloids through electrostatic stabilization. This discovery has enabled us to develop a facile approach to large-scale production of aqueous graphene dispersions without the need for polymeric or surfactant stabilizers. Our findings make it possible to process graphene materials using low-cost solution processing techniques, opening up enormous opportunities to use this unique carbon nanostructure for many technological applications.

/pdf/processable-aqueous-dispersions-of-graphene-nanosheets-4pl49qkwvn.pdf

Processable aqueous dispersions of graphene nanosheets

Adsorption isotherms of methane and ethane in single-walled carbon nanotubes (SWNTs) were measured by 1 H nuclear magnetic resonance (NMR) at room temperature. It is shown that the interior of SWNTs becomes available formethane and ethane adsorption after cutting of SWNTs. Such endohedral adsorption dominates methane and ethane adsorption in SWNTs, at least below 1 MPa. The average exchange time between molecules adsorbed inside SWNTs and free gas molecules outside was estimated to be on the order of 80 ms. It is shown that exposure to oxygen has no effect on methane and ethane endohedral adsorption in SWNTs, suggesting that the adsorption energy of oxygen molecules inside SWNTs is small compared to that of methane. 1 3 C NMR indicates that under atmospheric pressure and room temperature helium atoms could access the interstitial sites of SWNT bundles whereas H 2 , CO 2 , and N 2 molecules could not.

Adsorption in single-walled carbon nanotubes studied by NMR

Probing local magnetic cluster development in (CuZr)93−xAl7Gdx bulk metallic glasses by 27Al NMR

Synthesis of Micro-Porous Boron-Substituted Carbon (B/C) Materials Using Polymeric Precursors for Hydrogen Physisorption

Self-healing ability is a fascinating property of some materials. Structural materials with self-healing ability require a subtle combination of flow and stiffness characteristics. A vivid demonstration of self-healing is the automatic sealing of the bullet hole after bullet penetration of the target material. The ionomer Surlyn® satisfies the needs of both structural requirements and self-healing to a certain extent. The viscosity of Surlyn is very high at room temperature, a favorable property for structural applications but unfavorable for self-healing. However, when it was heated to 100°C and then cooled back down to room temperature, its viscosity remains temporarily low at room temperature for a few minutes, a favorable condition for healing. Here we report the measurement of such short-time relaxation effects on flow properties in Surlyn using an atomic force microscope (AFM)-based local thermal mechanical analyzer (LTA).

Local Thermal Analysis: Study of viscoelastic properties and time dependence in Surlyn

While the structural features and tunability of metal–organic frameworks (MOFs) make them promising materials for chemical warfare agent (CWA) hydrolysis, their stability and performance in conditions of varying humidity is an unsolved challenge. Understanding what design rules enable lasting hydrolytic functionality in evolving field conditions is consequently essential to developing practical MOFs for such applications. In this work, molecular dynamics simulations are carried out to examine the behavior of water at various loadings in the Zr-based MOF NU-1000. With its strong node-linker bonds, expansive pores, and balanced hydrophobicity, pristine NU-1000 possesses the characteristic attributes for structural stability and hydrolytic efficiency in the presence of environmental water. Adsorption and residence time results reveal that while NU-1000 is hydrophilic enough to allow water to adsorb, internal hydrophobicity discourages the distribution of H2O molecules to active sites at the metal nodes. Water–water interactions take precedence in NU-1000, forming a water cluster that grows with loading and distracts individual molecules from diffusing throughout the framework. On the other hand, self-diffusion coefficients and radial distribution function patterns suggest a lack of hydrogen bonding, with the clustered molecules having faster diffusion and less ordering than that of liquid-phase water. The limited interactions between water and the metal nodes indicate a lower likelihood of competition for sites impeding target species hydrolysis in NU-1000. Additionally, the partially vapor structural state of the aggregated water molecules in the expansive NU-1000 channels indicates a lower likelihood of pore filling by water that interferes with target species adsorption and diffusion. Such results evidence a strong potential of the NU-1000 Zr-MOF for superior performance in hydrolysis applications like toxic chemical decomposition. 

Yue Wu

Papers

Adsorption in single-walled carbon nanotubes studied by NMR

Probing local magnetic cluster development in (CuZr)93−xAl7Gdx bulk metallic glasses by 27Al NMR

Synthesis of Micro-Porous Boron-Substituted Carbon (B/C) Materials Using Polymeric Precursors for Hydrogen Physisorption

Local Thermal Analysis: Study of viscoelastic properties and time dependence in Surlyn

Vapor-Like Water in the NU-1000 Zr-MOF: A Molecular Level Understanding of Balanced Hydrophobicity in Humid Conditions