In-plane intercalate lattice modes in graphite-bromine using Raman spectroscopy

Eklund, P. C.; Kambe, N.; Dresselhaus, G.; Dresselhaus, M. S.

doi:10.1103/physrevb.18.7069

Cited by 71 publications

(35 citation statements)

References 25 publications

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“…rather than remaining at stage 2 with a lower bromine density per layer. 2,11,28 We note that frequency calculations incorporating the energetic double derivatives of surrounding carbon atoms gave identical values to within 1 cm −1 , showing that the Br 2 stretch mode is decoupled from the surrounding carbon lattice, consistent with the literature. Band-structure calculations of Br 2 layers between graphite sheets (not shown here) give a bromine related state, which pins the Fermi level just below that of perfect graphite (∼0.1 eV), indicating charge transfer from graphite to Br 2 .…”

Section: Bromine In Graphitesupporting

confidence: 71%

“…The C-C layer distance refers to the layers separated by bromine. Experimental values from EXAFS, 10 Raman, 11,13 and XRD. 6,9,12,26 At these low concentrations, Br 2 intercalation is endothermic.…”

Section: Bromine In Graphitementioning

confidence: 99%

“…This suggests that, at room temperature, Br 2 in graphite will be mobile and is consistent with the observation of a broad and somewhat complicated Raman peak. 11 We explored all possible layer stacking combinations for stage-1 and stage-2 intercalated graphites. Bromine molecules are most stable with AA-stacked graphite on each side, while unbrominated graphite layers preferentially are AB stacked.…”

Section: Bromine In Graphitementioning

confidence: 99%

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Bromination of graphene and graphite

et al. 2011

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We present a density-functional theory study of low-density bromination of graphene and graphite, finding significantly different behavior in these two materials. In graphene, we find a new Br 2 form where the molecule sits perpendicular to the graphene sheet with an extremely strong molecular dipole. The resultant Br + -Br − has an empty p z orbital located in the graphene electronic π cloud. Bromination opens a small (86-meV) band gap and strongly dopes the graphene. In contrast, in graphite, we find Br 2 is most stable parallel to the carbon layers with a slightly weaker associated charge transfer and no molecular dipole. We identify a minimum stable Br 2 concentration in graphite, finding low-density bromination to be endothermic. Graphene may be a useful substrate for stabilizing normally unstable transient molecular states.

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Section: Bromine In Graphitesupporting

confidence: 71%

Section: Bromine In Graphitementioning

confidence: 99%

Section: Bromine In Graphitementioning

confidence: 99%

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Bromination of graphene and graphite

et al. 2011

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“…We attribute these to adsorbed Br species, in agreement with previous studies suggesting the formation of chain channels of bromine in intercalated graphite compounds. 40,45 Furthermore, the line profile comparison of pristine and brominated FLG (Figure 2c), shows an increased average value of apparent step height by 0.18 nm which matches closely with the atomic radius of bromine, and is direct evidence of Br intercalation beneath graphene sheets. The pristine FLG transferred to a glass substrate appears to be somewhat patchy and wrinkled, as can be seen in SEM (Figure 2d) and AFM (Figure S5a) images.…”

Section: Resultsmentioning

confidence: 60%

Bromination of Graphene: A New Route to Making High Performance Transparent Conducting Electrodes with Low Optical Losses

Mansour

Dey

Amassian

et al. 2015

ACS Appl. Mater. Interfaces

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The high optical transmittance, electrical conductivity, flexibility and chemical stability of graphene have triggered great interest in its application as a transparent conducting electrode material and as a potential replacement for indium doped tin oxide. However, currently available large scale production methods such as chemical vapor deposition produce polycrystalline graphene, and require additional transfer process which further introduces defects and impurities resulting in a significant increase in its sheet resistance. Doping of graphene with foreign atoms has been a popular route for reducing its sheet resistance which typically comes at a significant loss in optical transmission. Herein, we report the successful bromine doping of graphene resulting in air-stable transparent conducting electrodes with up to 80% reduction of sheet resistance reaching ~180 Ω/□ at the cost of 2-3% loss of optical transmission in case of few layer graphene and 0.8% in case of single layer graphene. The remarkably low tradeoff in optical transparency leads to the highest enhancements in figure of merit reported thus far. Furthermore, our results show a controlled increase in the workfunction up to 0.3 eV with the bromine content. These results should help pave the way for further development of graphene as potentially a highly transparent substitute to other transparent conducting electrodes in optoelectronic devices. View presentation video on SPIE's Digital

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“…A back scattering geometry was used similar to the one described in the literature (15 fitted with circular quartz windows. Spectra were recordcd on low laser output power to prevent de-intercalation.…”

Section: ( B ) Instrumentationmentioning

confidence: 99%

The intercalation of bromine fluorosulfates into graphite

Karunanithy¹,

Aubke²

1983

Can. J. Chem.

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The action of bromine(1)fluorosulfate on graphite has led to the synthesis of several novel intercalation compounds. The intercalation of bromine(1)fluorosulfate at room temperature results in a first stage compound, C12BrSO3F, while at higher temperatures (~110 °C) C20BrF(SO3F)2 forms instead. Oxidation of C12BrSO3F with S2O6F2 yields C16Br(SO3F)3 and this reaction can be reversed by reacting the latter with an excess of Br2.Graphite trifluoromethylsulfate C12SO3CF3 is formed in the solvolysis of C12BrSO3F with an excess of trifluoromethyl-sulfuric acid. First stage nature of these compounds has been confirmed by the X-ray identity period along C axis and [Formula: see text], vibrational lattice mode in the Raman spectra. The use of 19F nmr in identifying the chemical species in the inter-lamellar space has been demonstrated. The planar electrical conductivity of these compounds has been observed to be three to six times higher than that of graphite.

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In-plane intercalate lattice modes in graphite-bromine using Raman spectroscopy

Cited by 71 publications

References 25 publications

Bromination of graphene and graphite

Bromination of graphene and graphite

Bromination of Graphene: A New Route to Making High Performance Transparent Conducting Electrodes with Low Optical Losses

The intercalation of bromine fluorosulfates into graphite

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