Formation of graphane and partially hydrogenated graphene by electron irradiation of adsorbates on graphene

Jones, Jason D.; Mahajan, Kamal; Williams, W.H.; Ecton, P.A.; Mo, Yudong; Pérez, Jose

doi:10.1016/j.carbon.2010.03.010

Cited by 88 publications

(56 citation statements)

References 22 publications

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“…As a matter of fact, dissociation of adsorbed water molecules on graphene by electron irradiation in Ref. 50 has been attained only for very high primary beam energies (E p =5000 eV).…”

Section: Resultsmentioning

confidence: 99%

Water adsorption on graphene/Pt(111) at room temperature: A vibrational investigation

et al. 2011

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Water interaction with quasi-freestanding graphene deposited on Pt(111) has been investigated by using vibrational spectroscopy. Loss measurements show that water molecules dosed at room temperature can dissociate giving rise to C-H bonds. The formation of the C-H bonds strongly attenuates the optical phonons of the graphene sheet. On the other hand, at 100 K water has been found to adsorb only in molecular state. Present findings should be taken into account in engineering graphene-based devices which should work at atmospheric pressure and at room temperature

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“…As a matter of fact, dissociation of adsorbed water molecules on graphene by electron irradiation in Ref. 50 has been attained only for very high primary beam energies (E p =5000 eV).…”

Section: Resultsmentioning

confidence: 99%

Water adsorption on graphene/Pt(111) at room temperature: A vibrational investigation

et al. 2011

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“…10,11 Graphene that is H terminated on only one side has also been proposed for use in spin-polarized devices with the structure known as graphone, 12 or as a gapped semiconductor material with full H coverage.…”

mentioning

confidence: 99%

“…3 Further theoretical studies have examined its structural, magnetic, and optical properties, [4][5][6][7][8][9] and its experimental synthesis has also been investigated. 10,11 Graphene that is H terminated on only one side has also been proposed for use in spin-polarized devices with the structure known as graphone, 12 or as a gapped semiconductor material with full H coverage. 13 In this Rapid Communication we propose a way of H desorption, which is mainly from one side of a suspended graphane sheet, with the use of an asymmetric pulse of the femtosecond laser by performing first-principles simulations.…”

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confidence: 99%

Laser-induced preferential dehydrogenation of graphane

2012

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We have used first-principles simulations based on time-dependent density functional theory to show that short laser pulses can trigger preferential hydrogen desorption from the upper or lower side of suspended graphane (H-terminated graphene). This control is achieved by using intense ultrashort p-polarized laser pulses (∼2 fs) with an asymmetric time envelope. The dynamical Stark effect induced by the pulse creates an asymmetric charge distribution and force field on the H ions, even at low laser fluence. At finite temperatures the carbon-hydrogen stretching softens, favoring H desorption from one side. This transient geometry can be modified by halogen functionalization, which results in a two-dimensional dipolar structure. Single-layer graphene is fabricated by mechanically peeling off a layer of carbon from pyrolytic graphite.1 Graphene's unique electronic, chemical, and mechanical properties and its potential applications have been extensively studied. Chemically modified graphene has been investigated, 2 and hydrogen (H)-terminated graphene, known as graphane, has also been found to be theoretically stable.3 Further theoretical studies have examined its structural, magnetic, and optical properties, 4-9 and its experimental synthesis has also been investigated. 10,11 Graphene that is H terminated on only one side has also been proposed for use in spin-polarized devices with the structure known as graphone, 12 or as a gapped semiconductor material with full H coverage. 13In this Rapid Communication we propose a way of H desorption, which is mainly from one side of a suspended graphane sheet, with the use of an asymmetric pulse of the femtosecond laser by performing first-principles simulations. Further chemical modification of this side with other reactive species can reach the heterogeneously terminated graphene, which was recently studied.14 We emphasize that this asymmetrically biased desorption is thermodynamically difficult and thus has not been considered in former theoretical studies for stability, 15,16 because the carbon-hydrogen (C-H) bond is the same on both sides. The femtosecond laser pulse has an asymmetric electric field (E-field) time envelope in order to induce dehydrogenation on one side of the graphane in our first-principles molecular dynamics calculations, based on the Ehrenfest time-dependent density functional theory (E-TDDFT) framework. 17,18 In this work, the z axis is set normal to the graphane sheet with the sheet at z = 0, and z > 0 and z < 0 are taken as the upper and lower regions, respectively (Fig. 1). An E-field polarized normal to the graphane sheet with the envelope shown in Fig. 2 results in a positive (upward) force on the ions and a negative force on the electrons. The H atoms in the upper region are desorbed from the sheet by this pulse, whereas the H atoms in the lower region remain bound. Thus, the upper graphene region remains chemically active, making this graphone sheet transient, which can be used for further functionalization. 19 We provide a complete microscopi...

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“…A strong increase in the D peak after hydrogen exposure suggests that hydrogen, a component of water, could be the main catalyst. It should be noted that in previous experiments we have conducted in which exfoliated monolayer graphene was pre-heated, exposed to various gases and irradiated in a similar manner, we found that molecular hydrogen and nitrogen exposure do not produce a D peak, but water vapor exposure does [25]. The lack of appearance of a D peak in graphene after molecular hydrogen and nitrogen exposure may be due to the ease at which these gases desorb from graphene due to their weak physisorption.…”

Section: E-gun Resultsmentioning

confidence: 54%

Low-energy electron irradiation of preheated and gas-exposed single-wall carbon nanotubes

Ecton

Beatty

Verbeck

et al. 2016

Applied Surface Science

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Ecton, Philip A. Low-Energy Electron Irradiation of Preheated and Gas-Exposed Single-Wall Carbon Nanotubes. Doctor of Philosophy (Physics), December 2016, 110 pp., 53 figures, 40 numbered references, bibliography.We investigate the conditions under which electron irradiation of single-walled carbon nanotube (SWCNT) bundles with 2 keV electrons produces an increase in the Raman D peak.We find that an increase in the D peak does not occur when SWCNTs are preheated in situ at 600 C for 1 h in ultrahigh vacuum (UHV) before irradiation is performed. Exposing SWCNTs to air or other gases after preheating in UHV and before irradiation results in an increase in the D peak. Small diameter SWCNTs that are not preheated or preheated and exposed to air show a significant increase in the D and G bands after irradiation. X-ray photoelectron spectroscopy shows no chemical shifts in the C1s peak of SWCNTs that have been irradiated versus SWCNTs that have not been irradiated, suggesting that the increase in the D peak is not due to chemisorption of adsorbates on the nanotubes.

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Formation of graphane and partially hydrogenated graphene by electron irradiation of adsorbates on graphene

Cited by 88 publications

References 22 publications

Water adsorption on graphene/Pt(111) at room temperature: A vibrational investigation

Water adsorption on graphene/Pt(111) at room temperature: A vibrational investigation

Laser-induced preferential dehydrogenation of graphane

Low-energy electron irradiation of preheated and gas-exposed single-wall carbon nanotubes

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