Bromine polycondensation in pristine and fluorinated graphitic carbons

Sedelnikova, Olga V.; Ewels, Christopher P.; Pinakov, D. V.; Chekhova, G. N.; Flahaut, Emmanuel; Окотруб, А. В.; Bulusheva, L. G.

doi:10.1039/c9nr01922g

Cited by 14 publications

(12 citation statements)

References 62 publications

(95 reference statements)

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“…At this fluorine content, the sp 2 -hybridized regions consist of several fused carbon hexagons surrounded by CF groups. According to DFT calculations, bromine molecules move over the surface of a graphene nanoregion to the CF border and spontaneously interact there to form Br 3 –Br 3 chains . The vibrations in such chains are in good agreement with the experimental values observed in the Raman spectra.…”

Section: Introductionsupporting

confidence: 73%

“…Polybromide chains were detected by X-ray diffraction (XRD) studies of stage-2 bromine–graphite intercalants; the Raman spectra of such compounds showed at least two components of the Br–Br vibrations. Interestingly, a similar complex shape of the bromine band was observed in the Raman spectra of bromine-FGICs when the fluorine content x was below 0.5 in the C 2 F x layers . At this fluorine content, the sp 2 -hybridized regions consist of several fused carbon hexagons surrounded by CF groups.…”

Section: Introductionsupporting

confidence: 64%

“…Three samples of different compositions were obtained at room temperature according to the procedure described elsewhere . The first stage of the synthesis consisted in the activation of natural graphite with Br 2 vapor to increase the intersheet spacing.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Contribution of Embedded Bromine Molecules to the Dielectric Properties of Fluorinated Graphite Intercalation Compounds

et al. 2023

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Here, we study the dielectric properties of fluorinated graphites C2F x with different fluorine contents (x ≈ 1.05, 0.85, and 0.60) and embedded bromine molecules by impedance spectroscopy. An analysis of the results using the Maxwell-Garnett approximation made it possible to estimate the contributions of the fluorinated graphite matrix and bromine guests to the dielectric permittivity of the compound. The permittivity of the C2F x matrix increases with decreasing fluorine content and does not depend on temperature. The change in the permittivity upon cooling/heating of the samples is provided by the polarization of bromine molecules Br2. The significant temperature-dependent dielectric response of C2F0.60 is associated with the formation of bromine and polybromide ions, such as Br2 – and Br3 –, in the interlayer space of the matrix. The decrease in the permittivity at low temperature is explained by the freezing of the ion mobility.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionsupporting

confidence: 64%

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Contribution of Embedded Bromine Molecules to the Dielectric Properties of Fluorinated Graphite Intercalation Compounds

et al. 2023

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“…For ICl-C 9.8 GIC, a similar structure with an AαAβ stacking order is proposed. Structural elucidation is challenging based solely on experimental data; thus, density functional theory (DFT) calculations were performed using the AIMPRO package, − an approach previously successfully applied to other halogenated nanocarbons. , We address the choice of exchange–correlation functional and dispersion description further in the Supporting Information, including benchmarking methods to experimentally measurable quantities (see also the Supporting Information). Different ICl structures were examined in both graphite and graphene systems, all of which show exothermic binding compared to isolated ICl.…”

Section: Resultsmentioning

confidence: 99%

Chainlike Structure Formed in Iodine Monochloride Graphite Intercalation Compounds

et al. 2021

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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“…Additionally, the Raman spectrum of brominated samples exhibited a peak at 153 cm 1 , attributed to polybromine Br n chains [45,48]. Our recent calculations have shown the chains are mainly composed of the Br 3 based species [49]. Bromine related peaks overlap with RBMs from the outer nanotubes, which does not allow revealing changes in their electronic structure as the result of bromination.…”

Section: Instrumentationmentioning

confidence: 90%

Effect of ultrasound pretreatment on bromination of double-walled carbon nanotubes

et al. 2020

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Carbon nanotubes Bromlnation Br 2 adsorption X-ray photoelectron spectroscopy Denslty functional theory calculatlons Bromination of double-walled carbon nanotubes (DWCNTs) was carried out using a saturated vapor of Br2 at room temperature with or without a pretreatment in bromine water. X-ray photoelectron spectroscopy revealed that ultrasound pretreatment modified the chemical state of bromine in the product. The binding energies of the Br 3d electrons in the pre-sonicated DWCNT sample were between those characteristic of the covalent C-Br bonds and the negatively charged Br2 molecules, observed when the pretreatment was not performed. Raman spectroscopy, however, clearly evidenced Br-Br vibrations in both brominated samples. Calculations of CNT-Br2 models within density functional theory were used to propose that the electronic state of a Br2 molecule depends on the adsorption site. The bromine molecules prefer to be located near edge hydroxyl groups, which acept the electron density from Br2• This increases the binding energy of Br 3d levels as compared to that for Br2 molecules in other adsorption sites.

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Bromine polycondensation in pristine and fluorinated graphitic carbons

Abstract: We reveal two distinct intercalated bromine species and propose bromination mechanisms of fluorinated carbons depending on the fluorination level.

Cited by 14 publications

References 62 publications

Contribution of Embedded Bromine Molecules to the Dielectric Properties of Fluorinated Graphite Intercalation Compounds

Contribution of Embedded Bromine Molecules to the Dielectric Properties of Fluorinated Graphite Intercalation Compounds

Chainlike Structure Formed in Iodine Monochloride Graphite Intercalation Compounds

Effect of ultrasound pretreatment on bromination of double-walled carbon nanotubes

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