Residual acetone produces explosives during the production of graphite oxide (original) (raw)
2003
The chemical reduction of graphite oxide (GO) to graphite by either NaBH4 or hydroquinone and also its surface modification with neutral, primary aliphatic amines and amino acids are described. Treatment of GO with NaBH4 leads to turbostatic graphite that upon calcination under an inert atmosphere is transformed to highly ordered graphitic carbon, while the reduction with hydroquinone yields directly crystalline graphite under soft thermal conditions. On account of the surface-exposed epoxy groups present in the GO solid, its surface modification with neutral, primary aliphatic amines or amine-containing molecules (amino acids and aminosiloxanes) takes place easily through the corresponding nucleophilic substitution reactions. In this way, valuable GO derivatives can be obtained, like molecular pillared GO, organically modified GO affording in organic solvents stable organosols or hydrophilic GO affording in water stable hydrosols and possessing direct cation exchange sites. The potential combination of surface modification and chemical reduction of GO in producing novel graphite based materials is also presented.
The chemistry of graphene oxide
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).
Chemical methods for the production of graphenes
Nature Nanotechnology, 2010
Several authors have stated that homogeneous colloidal suspensions of graphene oxide in aqueous and various organic solvents can be achieved by simple sonication of graphite oxide . The hydrophilic graphene oxide can be easily dispersed in water
Improved Synthesis of Graphene Oxide
An improved method for the preparation of graphene oxide (GO) is described. Currently, Hummers' method (KMnO 4 , NaNO 3 , H 2 SO 4 ) is the most common method used for preparing graphene oxide. We have found that excluding the NaNO 3 , increasing the amount of KMnO 4 , and performing the reaction in a 9:1 mixture of H 2 SO 4 /H 3 PO 4 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 KMnO 4 . 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 construction of devices composed of the subsequent CCG.
Graphite Oxide and Aromatic Amines: Size Matters
Advanced Functional Materials, 2014
currently one of the most promising is the chemical exfoliation of graphite passing the oxidation of the graphene sheets in order to form graphene oxide. [ 8,11,12 ] Graphene or graphite oxide (GO) is a layered material achieved through strong oxidation of graphite. [ 13-15 ] GO is characterized by the presence of oxygen-containing moieties, mostly hydroxyl and epoxy groups on the basal plane, and carboxyl groups prevalently at the edges of the carbon sheets. These groups convert hydrophobic graphite into highly soluble graphite oxide in several polar and nonpolar solvents, including water. [ 16,17 ] By now the attachment of functional groups is exploited by the well-established intercalation chemistry [ 18-20 ] leading to graphenebased hybrid materials for electrochemical sensors and biosensors or fi llers in composite materials for engineering applications, supercapacitors, energy storage and environmental applications. [ 8,21-26 ] Although the adsorption of organic molecules on carbon surfaces has been studied extensively for many years [ 27-31 ] no mechanism for covalent or non-covalent functionalization of graphene sheets through chemical grafting or π-π interactions respectively, using aromatic molecules has been reported up to now. Studies on carbon nanotubes have shown strong adsorption affi nity with many organic contaminants including polycyclic aromatic hydrocarbons [ 23,32-35 ] where the high adsorptive interactions of carbon nanotubes and aromatic molecules derive from the π-π electron donor-acceptor interaction between the conjugated core of the molecules (donors) and the carbon nanotubes (acceptors). [ 23,36,37 ] In this work, we demonstrate for the fi rst time the mechanism, by which two aromatic molecules, aniline and naphthalene amine, interact with the graphite oxide matrix and form new intercalated hybrid nanostructures. The structure and properties of this new class of materials may lead to potentially promising applications in water treatment, catalysis, solid state gas sensors, and energy storage devices. 2. Results and Discussion X-ray diffraction (XRD) data were collected to investigate the intercalation of aniline and naphthalene amine molecules into the interlayer space of graphite oxide. Figure 1 displays the XRD pattern of graphite oxide (GO), and of graphite oxide after mixing with aniline (GO_A) and naphthalene amine
Molecules, 2020
We exploited a classic chemistry demonstration experiment based on the reaction of acetylene with chlorine to obtain highly crystalline graphite at ambient conditions. Acetylene and chlorine were generated in-situ by the addition of calcium carbide (CaC2) in a concentrated HCl solution, followed by the quick addition of domestic bleach (NaClO). The released gases reacted spontaneously, giving bursts of yellow flame, leaving highly crystalline graphite deposits in the aqueous phase. This was a rather benign alternative towards synthetic graphite, the latter usually being prepared at high temperatures. The synthetic graphite was further utilized to obtain graphene or conductive inks.
Structure of Graphite Oxide Revisited
Graphite oxide (GO) and its derivatives have been studied using 13 C and 1 H NMR. NMR spectra of GO derivatives confirm the assignment of the 70 ppm line to C-OH groups and allow us to propose a new structural model for GO. Thus we assign the 60 ppm line to epoxide groups (1,2-ethers) and not to 1,3ethers, as suggested earlier, and the 130 ppm line to aromatic entities and conjugated double bonds. GO contains two kinds of regions: aromatic regions with unoxidized benzene rings and regions with aliphatic six-membered rings. The relative size of the two regions depends on the degree of oxidation. The carbon grid is nearly flat; only the carbons attached to OH groups have a slightly distorted tetrahedral configuration, resulting in some wrinkling of the layers. The formation of phenol (or aromatic diol) groups during deoxygenation indicates that the epoxide and the C-OH groups are very close to one another. The distribution of functional groups in every oxidized aromatic ring need not be identical, and both the oxidized rings and aromatic entities are distributed randomly. †
Synthesis of Graphene by Reduction of Graphene Oxide Using Non-Toxic Chemical Reductant
Springer eBooks, 2018
Graphene has generated a huge interest among the scientific community since its discovery in 2004 by Novoselov et al. [1]. Due to its unique, mechanical, chemical, thermal, optical, and electrical properties, it is having a very wide range of applications in electrostatic discharge (ESD), electromagnetic interference shielding (EMI), electronic devices, sensors, energy storages, biomedicals, etc. [2]. Graphenebased ESD and EMI materials find application in cell phone parts and coating to shield frequency for aerospace and electronic devices. Graphene can also be used as reinforcements to form a composite coating with polymer [3] and metal matrix [4]. Single-and few-layer graphene sheets can be successfully prepared by physical techniques such as epitaxial growth [5], mechanical cleavage [1], and chemical vapor deposition [6]. However, it is difficult to yield a scalable quantity of graphene by these physical methods. The most common approach to produce a scalable quantity of graphene is by chemical oxidation of graphite which gives oxidized graphite (graphene oxide in disperse form) and thereafter treating it with reducing agent to yield few-layer graphene or reduced graphene oxide (RGO) [7]. GO is an exfoliated layer of carbon with water molecules and oxygen functional groups. The basal plane of GO mostly consists of epoxy and hydroxyl groups, and the sheet edge of GO consists of carboxy, carbonyl, phenol, and quinine. Due to the distribution of these oxygen-rich functional group which is adsorbed on the surface of GO, it is non-conductive and hydrophilic in nature [8].
Journal of Alloys and Compounds, 2012
Liquid-phase processing of graphite and graphite derivatives is one of the most promising methodologies for the mass production of graphene. Here, we present a brief overview of the main developments in this research area over the last few years, together with our own contributions to the field. Particularly, we discuss the preparation of graphenes both in aqueous and organic media by reduction of exfoliated graphite oxide as well as by direct exfoliation of pristine graphite, highlighting some of the obstacles that have been encountered along the way and the approaches proposed to overcome them. Some fundamental aspects of graphenes derived from graphite oxide, specifically their structure and reactivity, are also considered.