A DFT-D study of hydrogen adsorption on functionalized graphene (original) (raw)
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Hydrogen adsorption on fluoro-graphene: an estimate by simulation
2015
International audienceAn estimate of the fluoro-graphene adsorption capacity for hydrogen is determined by Monte Carlo numerical simulations. Structure and symmetry of the atom arrangements in fluoro-graphene have been estimated by experiments and ab-initio computations. A comparison of effective and ab-initio potential for gas adsorption on fluoro-graphene materials is done before mesoscopic simulation setting up. These data allow to determine by ab-initio calculations the molecular interactions between gas molecules and the functionalized graphene materials or to estimate approximate effective atom-atom potentials to describe them. In this work on the basis of computed and effective interactions we calculated the fluoro-graphene adsorption properties of hydrogen up to high pressure both at room and low temperature. The estimation of hydrogen storage at 77K on fluoro-graphene is around 9 wt%
Density functional study of adsorption of molecular hydrogen on graphene layers
The Journal of Chemical Physics, 2000
Density functional theory has been used to study the adsorption of molecular H 2 on a graphene layer. Different adsorption sites on top of atoms, bonds and the center of carbon hexagons have been considered and compared. We conclude that the most stable configuration of H 2 is physisorbed above the center of an hexagon. Barriers for classical diffusion are, however, very small.
Hydrogen adsorption on fluoro-graphene: an estimate by simulation 氟石墨烯之上的氢吸附:仿真估计
2015
An estimate of the fluoro-graphene adsorption capacity for hydrogen is determined by Monte Carlo numerical simulations. Structure and symmetry of the atom arrangements in fluoro-graphene have been estimated by experiments and ab-initio computations. A comparison of effective and ab-initio potential for gas adsorption on fluoro-graphene materials is done before mesoscopic simulation setting up. These data allow to determine by ab-initio calculations the molecular interactions between gas molecules and the functionalized graphene materials or to estimate approximate effective atom-atom potentials to describe them. In this work on the basis of computed and effective interactions we calculated the fluoro-graphene adsorption properties of hydrogen up to high pressure both at room and low temperature. The estimation of hydrogen storage at 77K on fluoro-graphene is around 9 wt%.
First-principles DFT levels of calculations have been carried out in order to study the structural stability and electronic properties of hydrogen passivated graphene (H-graphene) clusters. Two different shaped clusters, rectangular and circular, consisting of 6 to 160 carbon atoms and hydrogen termination at the zigzag boundary edges have been studied. The relative stability of circular shaped cluster consisting 96 C-atoms have been predicted to be around 1.5% greater than that of rectangular shape cluster consisting same number of C-atoms. In comparing circular and rectangular cluster containing same number of C-atoms, the HOMO-LUMO gap of former have been predicted to be 2.159 eV and that of later just 0.346 eV. Adsorption of oxygen atom on H-graphene with different schemes including single sided, both sided and high concentration adsorption, was also studied systematically through first-principles DFT calculations by taking four different H-graphene clusters. The calculations showed that the most stable adsorption site for oxygen adatom on Hgraphene being B-site with adsorption energy 4.011 eV on the rectangular H-graphene cluster consisting 70 carbon atoms. Moreover, on increasing the size of H-graphene cluster, the adsorption energy of oxygen atom found to be increase. The distance of adatom from the nearest carbon atom of H-graphene sheet was 1.52 Å, however, the adatom height from the H-graphene basal plane was 1.97 Å. The bonding of oxygen adatom on H-graphene was through the charge transfer about 0.40 |e| from H-graphene to adatom and includes the negligible local distortion in the underlying planner H-graphene. Charge redistribution upon adsorption induces significant dipole moment 2.356 Debye on rectangular H-graphene cluster consisting 70 carbon atoms. The adsorption energy per O-atom in case of both side adsorption (one at B site and other at opposite B site below the sheet) was found to be around 2% greater than that of single O adsorption. The calculated values of dipole moment (0.881 Debye) and HOMO-LUMO gap (0.590 eV) in this case were almost one third of that for single O adsorption. The adsorption energy per O atom for both side adsorption model such that one at the B site and other at neighboring B site below the H-graphene sheet was found to be 4.650 eV, which is around 14% greater than that of both side adsorption discussed above and 16% greater than that of single O adsorption. The adsorption energy per O-atom, dipole moment and HOMO-LUMO gap in case of three oxygen atom adsorption on the alternate B site of central benzene ring of H-graphene cluster C70H22 have been estimated to be 4.522 eV, 5.898 Debye and 0.820 eV respectively.
RSC Adv., 2014
The physisorption of molecular hydrogen onto coronene is studied using a multi-scale theoretical approach with Density Functional Theory (DFT) calculations and Molecular Dynamics (MD) simulations. We consider two different kinds of model conformations for the approach of hydrogen towards the coronene i.e., systematic and random. For the systematic attack of hydrogen over coronene, the resulting potential energy profiles from DFT analysis are further found resembling to the Morse potential, and even to the largely flexible Murrell-Sorbie (M-S) potential. The resulting M-S fitting also shows a zero-point energy correction of ∼ 16-17 %. On the other hand, the potential energies from the random approach has been implemented into the Improved Lennard-Jones (ILJ) force field of DL − POLY package following a prior statistical treatment. The MD simulations have been performed at different temperatures from 10 to 390 K. For the interaction of seven hydrogen molecules with coronene, the DFT method shows an average interaction energy of −3.85 kJ/mol per H 2 , which is standing slightly below the Coupled Cluster value (CCSD(T)) of −4.71 kJ/mol that was calculated for a single molecule in the most favorable situation. Moreover, the MD calculations reveal a mean interaction energy of −3.69 kJ/mol per H 2 (a gross mean E c f g of −25.98 kJ/mol at T = 299.97 K), which is again in good agreement to the aforementioned DFT results, proving the quality of the used approach for the study of van der Waals interactions between hydrogen and graphene. (Spain).
DFT study of hydrogen adsorption on Ni/graphene
Applied Surface Science, 2018
DFT calculations with the GGA-PBE exchange correlation functional were used to study H2 adsorption on a Ni(111) surface, isolated Ni13 cluster, and graphenesupported Ni13. In comparison with Ni(111), hydrogen adsorption shows to be more stable on isolated Ni13 and graphene-supported Ni13. In the graphenesupported Ni13, pseudo charge density difference calculations showed accumulation of charge density around the Ni-graphene interfacial region. Dissociative H2 adsorption on Ni(111) and isolated Ni13 appears to be a nonactivated process, whereas an activation barrier is observed on the graphenesupported Ni13. Additionally, the effect of pre-adsorbed hydrogen in H2 adsorption in the mentioned systems was studied showing that it stabilizes the final state of adsorbed H and decreases the activation barrier.
Understanding adsorption of hydrogen atoms on graphene
The Journal of Chemical Physics, 2009
Adsorption of hydrogen atoms on a single graphite sheet (graphene) has been investigated by rstprinciples electronic structure means, employing plane-wave based, periodic density functional theory. A reasonably large 5x5 surface unit cell has been employed to study single and multiple adsorption of H atoms. Binding and barrier energies for sequential sticking have been computed for a number of congurations involving adsorption on top of carbon atoms. We nd that binding energies per atom range from ∼ 0.8 eV to ∼ 1.9 eV, with barriers to sticking in the range 0.0 − 0.2 eV. In addition, depending on the number and location of adsorbed hydrogen atoms, we nd that magnetic structures may form in which spin density localizes on a √ 3x √ 3R30 • sublattice, and that binding (barrier) energies for sequential adsorption increase (decrease) linearly with the site-integrated magnetization. These results can be rationalized with the help of the valence-bond resonance theory of planar π conjugated systems, and suggest that preferential sticking due to barrierless adsorption is limited to formation of hydrogen pairs.
First-Principles Study of Molecular Adsorption of Hydrogen/s on Co-Adatom Graphene
Journal of Institute of Science and Technology
The study of graphene and its allotropes help to understand fundamental science and their role in the industry. The adsorption of transition metal adatom on mono-layer graphene can tune the geometrical, electronic, and magnetic properties of the material according to the requirement for the practical applications. In the present work, the geometrical stability, electronic and magnetic properties, and also the redistribution of electronic charge of single cobalt atom (Co) adsorbed graphene with reference to pure graphene have been investigated to develop a model system for the effective storage of hydrogen. The density functional theory (DFT) based first-principles calculations by incorporating van der Waals (VDW) interactions within DFT-D2 levels of approximation implemented in the quantum ESPRESSO package was used. The band structure and density of states of cobalt-adatom graphene show that the material is metallic and magnetic with a total magnetic moment of 1.55 μB. The change in...
New Insights into H2S Adsorption on Graphene and Graphene-Like Structures: A Comparative DFT Study
C
The efficient removal of pollutants from different environments has been one of the great challenges for scientists in recent years. However, the understanding of the mechanisms underlying this phenomenon is still the subject of passionate debates, mainly due to the lack of experimental tools capable of detecting events at the atomic scale. Herein, a comparative theoretical study was carried out to capture the adsorption of H2S on metal oxide surfaces such as zinc oxide (ZnO) and beryllium oxide (BeO), as well as graphene and Ni-decorated graphene. A simulation based on density-functional theory (DFT) was carried out by adopting General Gradient Approximation (GGA) under the Perdew–Burke–Ernzerhof (PBE) function. The calculations quantified H2S adsorption on the considered metal oxide sheets as well as on the non-decorated graphene having a physical nature. In contrast, H2S adsorbed on Ni-decorated graphene sheet gave an adsorption energy of −1.64 eV due to the interaction of S and ...
Journal of Applied Physics, 2014
Previous Density Functional Theory (DFT) studies on metal decorated graphene generally use local density approximation (LDA) or generalized gradient approximation (GGA) functionals which can cause inaccuracies in hydrogen binding energies as they neglect van der Waals (vdW) interactions and are difficult to compare due to their widely varying simulation parameters. We investigated the hydrogen binding ability of several metals with a consistent set of simulations using the GGA functional and incorporated vdW forces through the vdW-DF2 functional. Metal adatom anchoring on graphene and hydrogen adsorption ability for both single and double sided decoration were studied for eight metals (Al, Li, Na, Ca, Cu, Ni, Pd, and Pt). It was found that the vdW correction can have a significant impact on both metal and hydrogen binding energies. The vdW-DF2 functional led to stronger metal adatom and hydrogen binding for light metals in comparison to GGA results, while heavier transition metals d...