Comparison of thermally and chemically reduced graphene oxides by thermal analysis and Raman spectroscopy
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Comparison of thermally and chemically reduced graphene oxides by thermal analysis and Raman spectroscopy Shereen Farah1 · Attila Farkas2 · János Madarász3 · Krisztina László1 Received: 12 October 2019 / Accepted: 16 April 2020 © The Author(s) 2020
Abstract Graphene oxide (GO) is not only an intermediate in top-down graphene preparation, but it is also acknowledged for its convenient application when the hydrophobicity of graphene is a drawback. Its preparation through the wet exfoliation of graphite inevitably leads to a product lacking several of the outstanding features of graphene. The destroyed graphene structure can be at least partially reconstructed by thermal and/or wet chemical reduction. Thermally reduced graphene oxide (TRGO) was obtained by mild heat treatment (300 °C) in argon, while chemically reduced graphene oxide (CRGO) was prepared by using a green reagent, ascorbic acid (AA). The parent GO and the two GO derivatives were compared by thermogravimetric analysis coupled with mass spectroscopy and Raman spectroscopy. Both reductive treatments resulted in enhanced thermal stability and higher C/O ratio. Although the chemical reduction with AA was more efficient in the elimination of the O functionalities, it also resulted in significant fragmentation of the graphene-like platelets. Keywords Reduced graphene oxide · Improved Hummers’ method · Thermal analysis (TG–DTG, TG–MS) · Raman spectroscopy
Introduction Since the first isolation of graphene by Geim and Novoselov et al. [1], the flat two-dimensional (2D) monolayer of carbon atoms has attracted great interest for its excellent electrical, mechanical, optical, and thermal properties [2, 3]. Graphene * Krisztina László [email protected] Shereen Farah [email protected] Attila Farkas [email protected] János Madarász [email protected] 1
Department of Physical Chemistry and Material Science, Budapest University of Technology and Economics, Budapest 1521, Hungary
2
Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budapest 1521, Hungary
3
Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Budapest 1521, Hungary
has outstanding potential in various environmentally related areas including catalysis, energy storage, and sensor-related applications [4]. Although graphene has proven its ability to be applied in many sectors, its hydrophobicity is often a critical factor in manufacturing. Hydrophilic graphene derivatives such as graphene oxide (GO) and reduced graphene oxides (RGOs) may help to overcome these problems. GO consists of a low number of graphene sheets with structural defects (single vacancies, Stone–Wales defects, etc.) [5, 6] and is decorated with various oxygen-containing functional groups in the basal planes and peripheries [7–10]. GO is most often prepared by oxidative exfoliation of graphite in highly aggressive media [11–15]. The properties of the obtained GO depend on the graphite precursor and the exfoliati
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