54 research outputs found
The thermodynamic and kinetic properties of hydrogen dimers on graphene
The thermodynamic and kinetic properties of hydrogen adatoms on graphene are
important to the materials and devices based on hydrogenated graphene. Hydrogen
dimers on graphene with coverages varying from 0.040 to 0.111 ML (1.0 ML cm) were considered in this report. The thermodynamic
and kinetic properties of H, D and T dimers were studied by ab initio
simulations. The vibrational zero-point energy corrections were found to be not
negligible in kinetics, varying from 0.038 (0.028, 0.017) to 0.257 (0.187,
0.157) eV for H (D, T) dimers. The isotope effect exhibits as that the kinetic
mobility of a hydrogen dimer decreases with increasing the hydrogen mass. The
simulated thermal desorption spectra with the heating rate K/s
were quite close to experimental measurements. The effect of the interaction
between hydrogen dimers on their thermodynamic and kinetic properties were
analyzed in detail.Comment: submitted to Surface Scienc
Ab initio simulations of the kinetic properties of the hydrogen monomer on graphene
The understanding of the kinetic properties of hydrogen (isotopes) adatoms on
graphene is important in many fields. The kinetic properties of
hydrogen-isotope (H, D and T) monomers were simulated using a composite method
consisting of density functional theory, density functional perturbation theory
and harmonic transition state theory. The kinetic changes of the magnetic
property and the aromatic bond of the hydrogenated graphene during the
desorption and diffusion of the hydrogen monomer was discussed. The vibrational
zero-point energy corrections in the activation energies were found to be
significant, ranging from 0.072 to 0.205 eV. The results obtained from
quantum-mechanically modified harmonic transition state theory were compared
with the ones obtained from classical-limit harmonic transition state theory
over a wide temperature range. The phonon spectra of hydrogenated graphene were
used to closely explain the (reversed) isotope effects in the prefactor,
activation energy and jump frequency of the hydrogen monomer. The kinetic
properties of the hydrogen-isotope monomers were simulated under conditions of
annealing for 10 minutes and of heating at a constant rate (1.0 K/s). The
isotope effect was observed; that is, a hydrogen monomer of lower mass is
desorbed and diffuses more easily (with lower activation energies). The results
presented herein are very similar to other reported experimental observations.
This study of the kinetic properties of the hydrogen monomer and many other
involved implicit mechanisms provides a better understanding of the interaction
between hydrogen and graphene.Comment: Accepted by J. Phys. Chem.
First-principles study of half-metallicity in semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets
Band Gap Characters and Ferromagnetic/Antiferromagnetic Coupling in Group-IV Monolayers Tuned by Chemical Species and Hydrogen Adsorption Configurations
Brain derived neurotrophic factor mediates accelerated recovery of regenerative electrical stimulation in an animal model of stress urinary incontinence
Electronic Structures and Structural Evolution of Hydrogenated Graphene Probed by Raman Spectroscopy
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