Hummers’ method

Graphite oxide (GO) is a layered structure that has recently attracted a considerable amount of interest in the scientific community. It can be prepared by Hummers method through its harsh oxidation with KMn04 in concentrated sulfuric acid [86]. While the... 

Bissessur and coworkers explored the inclusion of poly(2-ethylaniline) (PEA) and poly(2-propylaniline) (PPA) into GO, in addition to polyaniline [90]. The technique of intercalation differed from previously reported methods. They showed that polyaniUnes can be directly inserted into GO without the preparation of precursor phases. The polymers were first prepared from the monomers by oxidation with ammonium peroxydisulfate in acidic medium. GO, synthesized by using the Hummers method, was dispersed in deionized water with the aid of sonication. Colloidal suspensions of the polymers in NMF were then added to the aqueous GO suspensions. The reaction mixtures were then acidified and heated at 60 °C for 90 min. The intercalated phases were isolated via freezedrying. A similar process was used to intercalate polypyrrole into GO [91]. 

Figure 5.7 Schematic illustration of Brodie s method, Staudenmaier s method and Hummers method for the synthesis of graphene oxide hy chemical oxidation techniques.

Yu et al. synthesized Au NPs-rGO via gas phase chemical reduction method using oleylamine as a solvent cum reducing agent and utilized the composites material for micro-gravimetric detection of chemical vapour [38]. In the process, GO sheets were first prepared by modified Hummers method after which a measured amount of GO was added to a measured quantity of oleylamine solution and heated to 120°C in an oil bath. To the solution, HAuCT was added and heated to 180°C. The reaction was then cooled to... 

A generalization of the Hummer method that is useful for protein folding problems results when the entire configuration space is projected onto a selected low-dimensional (reaction) coordinate q. In this case, all equations derived above remain the same, with the distributions now pertaining to a subset of configuration space given by the condition q = q x). For example, the equilibrium distribution featured in the denominator of Eq. [19] is written as... 

Table 1 summarizes a survey of the synthetic approaches and resulting capacitance values of graphene-based electrodes (see also Refs. [5-7, 11, 14, 31, 76-80] for a review of synthetic approaches). Natural graphite is the most commonly used starting material, while more atypical materials such as CNTs [46] and platelet carbon nanofibers [55] have also been used. The (modified) Hummers method [81] is the most mutual method for oxidation of carbon, while the Staudenmaier [82] and Brodie [83] methods have also been applied. Reduction of the oxidized graphite oxide nanosheets is often conducted with hydrazine. 

Bulk graphite oxide is best prepared from purified natural graphite using the Hummers method Hummers, W. S. Offeman, R. E. J. Am. Chem. Soc. 1958,80,1339. For the mechanical exfoliation of bulk graphene oxide into sheets within an aqueous medium, see Stankovich, S. Dikin, D. A. Dommett, G. H. B. Kohlhaas, K. M. Zimney, E. J. Stach, E. A. Finer, R. D. Nguyen, S. T. Ruoff, R. S. Nature 2006,442, 282. 

Fig. 10 The structure of graphene oxide produced by Hummers method and the modification to the structure produced base washing. (Reproduced with permission.)... 

Oxidation of graphite with modified hummers method... 

Zou, Z.G., Yu, H.J., Long, F., Fan, Y.H., 2011. Preparation of graphene oxide by ultrasound-assisted hummers method. Chinese Journal of Inorganic Chemistry 27, 1753—1757. 

Researchers have focused more on the synthesis and reduction of graphene oxide because GO and reduced GO can be synthesized easily. GO is usually synthesized from the oxidation of graphite by strong oxidants based on the Brodie, Staudenmaier, or Hummers methods or some other modification of these methods. Hummers method has been more widely used and many modifications have been made to synthesize GO for designated appHcations (Tong et al., 2013). 

An alternative preparation method that is commonly used, owing to the ease of production, high yield and low cost, is based on the chemical oxidation of graphite to GO via one of the three principle methods developed by Brodie, Staudenmeier, and Hummers." The Hummers method is... 

Fig. 5 (A) Preparation of GO from graphite using the Hummers method. (B) high resolution XPS Cls core level spectrum of GO before (left) and after reduction using hydrazine (right). ...

GO was prepared from graphite powder through the modified Hummers method [183]. Graphene was synthesized via the chemical reduction of GO by sodium acetate trihydrate. A typical procedure was 1.10 g CH3C00Na 3H20 dispersed into 55 mL of GO dispersion (1 mg/mL). 

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