An electron diffraction study of graphitic oxide

Cruz, Francisco Aragón de la; Cowley, J. M.

doi:10.1107/s0365110x63001419

Cited by 27 publications

(11 citation statements)

References 3 publications

(3 reference statements)

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“…The 2:8 sample showed a little predominance of diffraction spots, which is attributed to the retention of graphene-like lattice substances within the oxidized GO domains (Figure S5d). The existence of such graphitic islands or unoxidized sp 2 domains within the oxidized GO sheets are substantially present as reported previously. , The 0:10 sample showed a set of sixfold symmetric diffraction points of a typical hexagonal configuration (Figure f), which could be attributed to the highest formation of super-lattice-type ordered arrays because of a larger amount of graphitic islands, as also supported by XRD and Raman analysis.…”

Section: Resultssupporting

confidence: 85%

Control of Functionalities in GO: Effect of Bronsted Acids as Supported by Ab Initio Simulations and Experiments

et al. 2019

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Graphene oxide (GO) is an attractive precursor for graphene, provided by the well-known wet-chemical oxidative process. The intercalation of acid in graphite is considered as a crucial step, and its subsequent oxidation holds special relevance in synthesis. So far, the above chemistry is dominated by usage of H 2 SO 4 . Recently, H 3 PO 4 appeared as a suitable intercalant for graphite. However, its role is not well understood in the formation of GO, especially when present as a co-acid with H 2 SO 4 . Additionally, a relatively lower toxicity of H 3 PO 4 as compared to H 2 SO 4 , elimination of toxic NaNO 3 usage, and a facile purification protocol are encouraging in terms of low-cost production of GO with a reduced environmental impact. Here, we report the systematic synthesis and characterization of GOs prepared with the variation in the ratio of H 2 SO 4 and H 3 PO 4 . Ab initio simulations revealed that intercalation is primarily affected because of the usage of a mixture of co-acids. Interestingly, the ratio of the acids dictated the nature of the functionalities, extent of the defects, and morphology of the GOs, accounting for a pronounced effect on thermal stability, contact angle, zeta potential, and hydrodynamic size. The oxidation mechanism showed a predominance of H 2 SO 4 content, whereas H 3 PO 4 is found to mainly govern the intercalation of graphite, thereby affecting the acid-based intercalation–oxidation chemistry of graphite. The as-prepared GO suspension exhibited a high adsorption capacity for methylene blue dye removal in water, suggesting its potential as an adsorbent material in water treatment. The utility of the two acids affects the acid-based intercalation–oxidation chemistry of graphite and simultaneously may open up new opportunities for synthesized GOs, on tenets of green chemistry, in a wide arena of applications.

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Section: Resultssupporting

confidence: 85%

Control of Functionalities in GO: Effect of Bronsted Acids as Supported by Ab Initio Simulations and Experiments

et al. 2019

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“…The C/O ratio was roughly calculated as approximately 2, which is consistent with that of fully oxidized graphite oxide estimated from previous studies. 34,35 Compositions of Mn 3 O 4 were estimated at about 41, 43 and 48% of the entire mass of composites for GO-Mn 3 O 4 A, B and C, respectively. Increase in the coverage and thickness of the Mn 3 O 4 layer led to the growth of the mass proportion.…”

Section: Resultsmentioning

confidence: 99%

One-step sonochemical synthesis of a graphene oxide–manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate)

et al. 2012

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Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn(3)O(4)) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn(3)O(4). An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn(3)O(4) phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn(3)O(4) were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn(3)O(4), while PET glycolysis with the Mn(3)O(4) without GO yielded 82.7% BHET.

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“…4,9,13,14,[28][29][30] Several reports claim that graphite oxide has an amorphous nature but reports on a TEM study of the graphite oxide reect that it has ordering, similar to graphite. 27,31,32 Therefore, although the reduction and oxidation process involves incorporation of defects and dislocations contribute as a disorder, the remnant oxygen bearing functional groups serve as an insulating area, rather than as a disordered area. Moreover because of the oxidation and reduction process, a ake to ake and interlayer layer interaction would be very weak.…”

Section: The Distributed Tunnel Junction Networkmentioning

confidence: 99%

Transition from direct to Fowler–Nordheim tunneling in chemically reduced graphene oxide film

et al. 2014

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We investigate charge transport in a chemically reduced graphene oxide (RGO) film of sub-micron thickness. The I-V curve of RGO film shows current switching of the order of ∼10(5) above the threshold voltage. We found that the observed I-V curve is consistent with quantum tunnelling based charge transport. The quantum tunnelling based Simmons generalized theory was used to interpret the charge transport mechanism which shows that the current switching phenomenon is associated with transition from direct to Fowler-Nordheim (F-N) tunneling. The absence of current switching in the I-V curve after stripping away the oxygen functional groups from chemically RGO film confirms that the presence of these groups and reduced interaction between adjacent layers of RGO play a key role in charge transport. Such metal-based current switching devices may find applications in graphene-based electronic devices such as high voltage resistive switching devices.

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An electron diffraction study of graphitic oxide

Cited by 27 publications

References 3 publications

Control of Functionalities in GO: Effect of Bronsted Acids as Supported by Ab Initio Simulations and Experiments

Control of Functionalities in GO: Effect of Bronsted Acids as Supported by Ab Initio Simulations and Experiments

One-step sonochemical synthesis of a graphene oxide–manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate)

Transition from direct to Fowler–Nordheim tunneling in chemically reduced graphene oxide film

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