Kinetic Monte Carlo studies of hydrogen abstraction from graphite

Cuppen, H. M.; Hornekær, Liv

doi:10.1063/1.2913238

Cited by 57 publications

(63 citation statements)

References 33 publications

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“…Indeed, as we show below, H atoms do not adsorb completely random on the surface. A number of TPD, AES, EELS and HREELS spectroscopy data (Andree et al, 2006;Güttler et al, 2004a;Zecho et al, 2004; is available, along with detailed kinetic Monte Carlo simulations (Cuppen & Hornekaer, 2008;Gavardi et al, 2009) of TP desorption curves and accurate studies of vibrational relaxation dynamics (Sakong & Kratzer, 2010) and reaction dynamics to form H 2 (Casolo et al, 2009b;Jackson & Lemoine, 2001;Martinazzo & Tantardini, 2005;2006a;Morisset et al, 2004;. Notice that even though we focused here on adsorption of H atoms the same holds for other simple, monovalent chemical species.…”

Section: Sticking Of Atomic and Molecular Speciesmentioning

confidence: 99%

The Effect of Atomic-Scale Defects and Dopants on Graphene Electronic Structure

Martinazzo¹,

Casolo²,

Tantardini³

2011

Physics and Applications of Graphene - Theory

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Graphene, being one-atom thick, is extremely sensitive to the presence of adsorbed atoms and molecules and, more generally, to defects such as vacancies, holes and/or substitutional dopants. This property, apart from being directly usable in molecular sensor devices, can also be employed to tune graphene electronic properties.Here we briefly review the basic features of atomic-scale defects that can be useful for material design. After a brief introduction on isolated p z defects, we analyse the electronic structure of multiple defective graphene substrates, and show how to predict the presence of microscopically ordered magnetic structures. Subsequently, we analyse the more complicated situation where the electronic structure, as modified by the presence of some defects, affects chemical reactivity of the substrate towards adsorption (chemisorption) of atomic/molecular species, leading to preferential sticking on specific lattice positions. Then, we consider the reverse problem, that is how to use defects to engineer graphene electronic properties. In this context, we show that arranging defects to form honeycomb-shaped superlattices (what we may call "supergraphenes") a sizeable gap opens in the band structure and new Dirac cones are created right close to the gapped region. Similarly, we show that substitutional dopants such as group IIIA/VA elements may have gapped quasiconical structures corresponding to massive Dirac carriers. All these possible structures might find important technological applications in the development of graphene-based logic transistors.

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Section: Sticking Of Atomic and Molecular Speciesmentioning

confidence: 99%

The Effect of Atomic-Scale Defects and Dopants on Graphene Electronic Structure

Martinazzo¹,

Casolo²,

Tantardini³

2011

Physics and Applications of Graphene - Theory

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“…It is now widely accepted that H 2 can only form on the surface of interstellar dust grains and particles, [10][11][12] which-with the exception of cold dense molecular clouds-are either carbon-coated silicate grains or carbonaceous particles or large PAHs. [13][14][15] This finding has stimulated a number of theoretical [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] and experimental 19,[34][35][36][37][38][39][40][41][42][43] studies on hydrogen graphitic systems aimed at elucidating the possible reaction pathways leading ultimately to molecule formation.…”

Section: Introductionmentioning

confidence: 99%

Understanding adsorption of hydrogen atoms on graphene

Casolo

Løvvik

Martinazzo

et al. 2009

The Journal of Chemical Physics

334

375

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Adsorption of hydrogen atoms on a single graphite sheet ͑graphene͒ has been investigated by first-principles electronic structure means, employing plane-wave based periodic density functional theory. A 5 ϫ 5 surface unit cell has been employed to study single and multiple adsorptions of H atoms. Binding and barrier energies for sequential sticking have been computed for a number of configurations involving adsorption on top of carbon atoms. We find that binding energies per atom range from ϳ0.8 to ϳ1.9 eV, with barriers to sticking in the range 0.0-0.15 eV. In addition, depending on the number and location of adsorbed hydrogen atoms, we find that magnetic structures may form in which spin density localizes on a ͱ 3 ϫ ͱ 3R30°sublattice and that binding ͑barrier͒ energies for sequential adsorption increase ͑decrease͒ linearly with the site-integrated magnetization. These results can be rationalized with the help of the valence-bond resonance theory of planar conjugated systems and suggest that preferential sticking due to barrierless adsorption is limited to formation of hydrogen pairs.

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“…Only recently, Casolo et al 24 , Roman et al 29 , Ferro et al 30 and Khazaei et al 31 used Density Functional Theory (DFT) to calculate the energetics of hydrogen clusters with three and four atoms, as well as one structure with six atoms on a graphene sheet. Cuppen et al 32 studied the formation of hydrogen clusters using Kinetic Monte Carlo methods. Luntz and co-workers 33 studied desorption of D 2 molecules from D clusters adsorbed on graphite, combining experimental and theoretical methods.…”

Section: Introductionmentioning

confidence: 99%

Structure and stability of small H clusters on graphene

et al. 2011

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The structure and stability of small hydrogen clusters adsorbed on graphene is studied by means of Density Functional Theory (DFT) calculations. Clusters containing up to six H atoms are investigated systematically -the clusters having either all H atoms on one side of the graphene sheet (cis-clusters) or having the H atoms on both sides in an alternating manner (trans-cluster). The most stable cis-clusters found have H atoms in ortho-and para-positions with respect to each other (two H's on neighboring or diagonally opposite carbon positions within one carbon hexagon) while the most stable trans-clusters found have H atoms in ortho-trans-positions with respect to each other (two H's on neighboring carbon positions, but on opposite sides of the graphene). Very stable trans-clusters with 13-22 H atoms were identified by optimizing the number of H atoms in orthotrans-positions and thereby the number of closed, H-covered carbon hexagons. For the cis-clusters, the associative H2 desorption was investigated. Generally, the desorption with the lowest activation energy proceeds via para-cis-dimer states, i.e. involving somewhere in the H clusters two H atoms that are positioned on opposite sites within one carbon hexagon. H2 desorption from clusters lacking such H pairs is calculated to occur via hydrogen diffusion causing the formation of para-cis-dimer states. Studying the diffusion events showed a strong dependence of the diffusion energy barriers on the reaction energies and a general odd-even dependence on the number of H atoms in the cis-clusters.

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Kinetic Monte Carlo studies of hydrogen abstraction from graphite

Cited by 57 publications

References 33 publications

The Effect of Atomic-Scale Defects and Dopants on Graphene Electronic Structure

The Effect of Atomic-Scale Defects and Dopants on Graphene Electronic Structure

Understanding adsorption of hydrogen atoms on graphene

Structure and stability of small H clusters on graphene

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