Reactions of Gas-Phase Atomic Hydrogen with Chemisorbed Hydrogen on a Graphite Surface

Ree, Jongbaik; Kim, Yoo Hang; Shin, Hyung Kyu

doi:10.5012/bkcs.2007.28.4.635

Cited by 6 publications

(3 citation statements)

References 43 publications

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“…The energy transfer to the surface is about 20% of the available energy, in agreement with the findings of ref . It changes only slowly with increasing E coll and is generally larger than that found in other studies, which limited somewhat the surface atoms motion. , Interestingly, the amount of energy left on the surface (∼0.9–1.0 eV) compares rather well with the puckering energy, i.e., the energy needed to move the C atom out of the pristine surface at a height it has when it binds a hydrogen atom. This shows that reaction is close to the sudden limit: the molecular product is formed on a time scale shorter than the one needed for surface relaxation, the carbon atom remains essentially frozen in its puckered configuration, and only at later times, when H 2 is far away from the surface, does it release its excess energy.…”

Section: Resultssupporting

confidence: 90%

Hydrogen Recombination and Dimer Formation on Graphite from Ab Initio Molecular Dynamics Simulations

2016

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We studied Eley-Rideal molecular hydrogen formation on graphite using ab initio molecular dynamics, in the energy range relevant for the chemistry of the interstellar medium and for terrestrial experiments employing cold plasma (0.02-1 eV). We found substantial projectile steering effects that prevent dimer formation at low energies, thereby ruling out any catalytic synthetic pathways that form hydrogen molecules. Ortho and para dimers do form efficiently thanks to preferential sticking, but only at energies that are too high to be relevant for the chemistry of the interstellar medium. Computed reaction cross sections and ro-vibrational product populations are in good agreement with available experimental data and capable of generating adsorbate configurations similar to those observed with scanning tunneling microscopy techniques.

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Section: Resultssupporting

confidence: 90%

Hydrogen Recombination and Dimer Formation on Graphite from Ab Initio Molecular Dynamics Simulations

2016

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“…It was found that at low temperatures ER is the dominant reactive pathway due to the attractive potential of the chemisorbed hydrogen and the strong steering effects experienced by the approaching hydrogen. 31,39 Several other reactions not contributing to H 2 abstraction have been found such as H−H exchange 40 and collisioninduced desorption (CID) 41 where both hydrogens leave the surface as atoms. CID, for example, is more prevalent at higher energies as the ER pathway is vibrationally inhibited.…”

Section: Introductionmentioning

confidence: 99%

“…Several other reactions not contributing to H 2 abstraction have been found such as H–H exchange and collision-induced desorption (CID) where both hydrogens leave the surface as atoms. CID, for example, is more prevalent at higher energies as the ER pathway is vibrationally inhibited .…”

Section: Introductionmentioning

confidence: 99%

Exploration of Graphene Defect Reactivity toward a Hydrogen Radical Utilizing a Preactivated Circumcoronene Model

2021

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A preexisting chemisorbed defect is well-known to increase the reactivity of graphene which is normally chemically inert. Specifically, the presence of chemisorbed hydrogen atoms forming an sp3-hybridized C–H bond is known to increase the reactivity of neighboring carbon atoms toward additional hydrogenation with wide-ranging applications from materials science to astrochemistry. In this work, static DFT and DFT-based direct dynamics simulations are used to characterize the reactivity of a graphene sheet around an existing C–H bond defect. The spin density landscape shows how to guide subsequent H atom additions, always bonding most strongly to the carbon atom with greatest spin density. Molecular dynamics of an impinging H atom under thermal conditions with defect graphene was used to determine the statistics of probable reactions. The most frequent outcome is inelastic scattering (48%) and then Eley–Rideal (ER) abstraction of the chemisorbed H atom as vibrationally hot H2 (40%), while the least likely, but probably most interesting, result is formation of a novel C–H bond (12%). The C–H bonds always form in the β sublattice. The carbon atom in the para position shows to be most reactive toward the incoming H atom, followed by the ortho carbon, in agreement with the spin density computed in the static calculations. Globally, the graphene energy surface is repulsive, but the defects create local channels into this energy surface through which reactants can move locally through and react with the activated surface without a barrier.

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Investigation of ZPE and temperature effects on the Eley–Rideal recombination of hydrogen atoms on graphene using a multidimensional graphene–H–H potential

Sizun

Bachellerie

Aguillon

et al. 2010

Chemical Physics Letters

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Reactions of Gas-Phase Atomic Hydrogen with Chemisorbed Hydrogen on a Graphite Surface

Cited by 6 publications

References 43 publications

Hydrogen Recombination and Dimer Formation on Graphite from Ab Initio Molecular Dynamics Simulations

Hydrogen Recombination and Dimer Formation on Graphite from Ab Initio Molecular Dynamics Simulations

Exploration of Graphene Defect Reactivity toward a Hydrogen Radical Utilizing a Preactivated Circumcoronene Model

Investigation of ZPE and temperature effects on the Eley–Rideal recombination of hydrogen atoms on graphene using a multidimensional graphene–H–H potential

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