Dielectric relaxation characteristics of chemically reduced graphite oxide

Wei, Guidan; Yu, Ji; Gu, Min; Ai, Xiaoqian; Xu, Xibin; Tang, Tong B.

doi:10.1016/j.carbon.2015.08.031

Cited by 9 publications

(4 citation statements)

References 35 publications

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“…In recent years, new cost effective high quality functionalized few layered graphene (FG) was developed, which is an alternative to the more expensive defect-free monolayered graphene. Typically, FG was produced at markedly larger scale by the oxidation of graphite and followed by thermal [10][11][12] or chemical [13,14] reduction. However, the production of intermediate graphite oxide (GO) required the use of large amounts of strong acids, hazardous oxidizing agents [15] and frequently also toxic reducing agents such as sodium borohydride [14].…”

Section: Introductionmentioning

confidence: 99%

“…Typically, FG was produced at markedly larger scale by the oxidation of graphite and followed by thermal [10][11][12] or chemical [13,14] reduction. However, the production of intermediate graphite oxide (GO) required the use of large amounts of strong acids, hazardous oxidizing agents [15] and frequently also toxic reducing agents such as sodium borohydride [14]. Another approach towards FG preparation exploits dry ball milling of graphite under different gas atmospheres, which enables the one-step synthesis of functionalized graphene with multilayered structures bearing different functional groups.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Mechanochemically Functionalized Multilayer Graphene on the Tribological Properties of Silicon Carbide/Graphene Nanocomposites in Aqueous Environment

et al. 2018

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Dry milling of graphite in a ball mill represents a versatile one-step mechanochemical process for fabricating mechanochemically functionalized multilayer graphene (MG) bearing different functional groups. The variation of the milling parameters enables to control particle size, shape, functionality, specific surface area and dispersability of the MG functional fillers. In this study, MG was used as functional nanofiller for the production of SiC/MG nanocomposites. The nanocomposites exhibit significantly improved tribological behavior. The results of rotating pin on disc sliding tests show that with SiC/MG a noticeable improvement of friction and wear behavior under water-lubricated conditions like in slide bearings and face seals can be achieved. Sliding friction systems with the variant SiC+2% MG-CO 2 -120h appear to have the most promising tribological properties, due to the reduced size of the homogeneously distributed graphite particles, which promote the formation of advantageous surface states.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Mechanochemically Functionalized Multilayer Graphene on the Tribological Properties of Silicon Carbide/Graphene Nanocomposites in Aqueous Environment

et al. 2018

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“…Peak at 1581 cm −1 is typical for sp 2 carbon. Peaks associated with C–O and C=O vibrations confirming the existence of the carbonyl, carboxyl, epoxy and hydroxyl groups (respectively, 1728 and 1630 cm −1 for C=O and 1395, 1225, 1170 and 1042 cm −1 for C–O) [19–23]. In addition, peak at 1131 cm −1 can be interpreted as vibration from 5‐membered‐ring lactol at the edges [24].…”

Section: Resultsmentioning

confidence: 99%

Structure of nanographite synthesised by electrochemical oxidation and exfoliation of polycrystalline graphite

Radoń

Łukowiec

2017

Micro & Nano Letters

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The Letter presents the results of characterisation of intercalated and exfoliated graphite. The electrochemically exfoliated graphite (EEG) was synthesised in solution containing sulphuric acid and potassium chlorate(V). The number of graphene layers, degree of disordering and the presence of functional groups were determined using X-ray diffraction method, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-visible spectroscopy. High-resolution transmission electron microscopy and scanning electron microscopy were used to imaging morphology and structure of the synthesised material. The obtained micrographs indicate the presence of highly disordered areas near the edge of flakes and in-plane ordered lattice structure in the flat zone between disordered areas. X-ray diffraction patterns clearly indicate the presence of both nanographite and graphene oxide. The EEG was also characterised by relatively high thermal stability, which was confirmed using thermogravimetric analysis.

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“…15,16 In the nanocomposites, reduced absorptions at ∼ 3600 and 1226 cm −1 indicate ionic bonding of the cation in headgroup to C-O − group, and that at 1721 cm −1 suggests partial reduction of GO. 17 Regions of special interest are enlarged in Fig. 4, showing absorptions that relate to CH 2 stretching, scissoring and rocking vibration modes of methylene on the alkylammonium cations.…”

Section: Resultsmentioning

confidence: 99%

Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

Tian

et al. 2016

AIP Advances

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The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18) intercalated in graphite oxide (GO) have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16) or bilayers (when n = 18), with their long axis parallel to GO layers, and with cations of headgroups bonded ionically to C-O- groups of GO; backbones of the confined molecules remain free. All halides and intercalation compounds suffer dielectric loss at low temperature. Arrhenius plots of the thermal dependence of the loss peaks, which are asymmetric, produce apparent activation energies that rise with increasing n. Ngai’s correlated-state model helps to correct for effects of dipole-dipole interaction, leading to virtually identical values for actual activation energy of 110 meV ± 5%; the values are also almost the same as the barrier energy for internal rotation in the alkyl macromolecule. We conclude that the relaxation of the alkylammonium cations arises not from C3 reorientation of the CH3 at its headgroup, but from small-angle wobbling around its major axis, an intrinsic motion.

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Dielectric relaxation characteristics of chemically reduced graphite oxide

Cited by 9 publications

References 35 publications

Effect of Mechanochemically Functionalized Multilayer Graphene on the Tribological Properties of Silicon Carbide/Graphene Nanocomposites in Aqueous Environment

Effect of Mechanochemically Functionalized Multilayer Graphene on the Tribological Properties of Silicon Carbide/Graphene Nanocomposites in Aqueous Environment

Structure of nanographite synthesised by electrochemical oxidation and exfoliation of polycrystalline graphite

Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

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