Synthesis of Graphene Oxide GO by Modified Hummers Method and Its Thermal Reduction to Obtain Reduced Graphene Oxide rGO*Reportar como inadecuado




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Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon-oxygen ratio of the obtained graphene. Here, graphene oxide GO was prepared by oxidizing the purified natural flake graphite NFG by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 by volume mixture of H2SO4-H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide rGO was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction XRD, scanning electron microscopy SEM, high-resolution transmission electron microscopy HR-TEM, Fourier transform infrared spectroscopy FTIR, ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller BET surface area analysis and differential scanning calorimetry DSC and thermogravimetric analysis TGA.

KEYWORDS

Graphene Oxide GO, Reduced Graphene Oxide rGO, Exfoliated Graphite Nanoplatelets xGnP

Cite this paper

Alam, S. , Sharma, N. and Kumar, L. 2017 Synthesis of Graphene Oxide GO by Modified Hummers Method and Its Thermal Reduction to Obtain Reduced Graphene Oxide rGO*. Graphene, 6, 1-18. doi: 10.4236-graphene.2017.61001.





Autor: Syed Nasimul Alam, Nidhi Sharma, Lailesh Kumar

Fuente: http://www.scirp.org/



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