Hydrogen storage capacity of titanium met-cars

Akman, Nurten; Durgun, Engin; Yildirim, Taner; Çiraci, S.

doi:10.1088/0953-8984/18/41/017

Cited by 39 publications

(44 citation statements)

References 29 publications

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“…Much work has focused on carbon-based materials such as nanotubes, [4][5][6][7][8][9][10][11][12][13][14] C 60 , 15,16 metal hydrides, and metal-organic frameworks, 17,18 titanium metallocarbohedryne, 19,20 and polyacethylene. 21 The main obstacles in hydrogen storage are slow kinetics, poor reversibility, and high dehydrogenation temperatures for chemical hydrides.…”

Section: 3-11mentioning

confidence: 99%

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

2008

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In a recent letter ͓T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 ͑2005͔͒, the unusual hydrogen storage capacity of Ti decorated carbon nanotubes has been revealed. The present paper extends this study further to investigate the hydrogen uptake by light transition-metal atoms decorating various carbon-based nanostructures in different types of geometry and dimensionality, such as carbon linear chain, graphene, and nanotubes. Using first-principles plane-wave method we show that not only outer but also inner surface of a large carbon nanotube can be utilized to bind more transition-metal atoms and hence to increase the storage capacity. We also found that scandium and vanadium atoms adsorbed on a carbon nanotube can bind up to five hydrogen molecules. Similarly, light transition-metal atoms can be adsorbed on both sides of graphene and each adsorbate can hold up to four hydrogen molecules yielding again a high-storage capacity. Interestingly, our results suggest that graphene can be considered as a potential high-capacity H 2 storage medium. We also performed transition state analysis on the possible dimerization of Ti atoms adsorbed on the graphene and single-wall carbon nanotube.

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Section: 3-11mentioning

confidence: 99%

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

2008

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“…Interestingly, we found that even the dissociated structure can still absorb multiple H 2 , in which case, the system is somewhat similar to a Ti metallocarbohedryne ͑met-car͒ cluster. 27,28 …”

Section: Activation Energies and Reaction Paths Between Differentmentioning

confidence: 99%

Hydrogen absorption properties of metal-ethylene complexes

et al. 2007

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Recently, we have predicted [Phys. Rev. Lett. 97, 226102 (2006)] that a single ethylene molecule can form stable complexes with light transition metals (TMs) such as Ti and the resulting TM n -ethylene complex can absorb up to ~ 12 and 14 wt % hydrogen for n=1 and 2, respectively. Here we extend this study to include a large number of other metals and different isomeric structures. We obtained interesting results for light metals such as Li. The ethylene molecule is able to complex with two Li atoms with a binding energy of 0.7 eV/Li which then binds up to two H2 molecules per Li with a binding energy of 0.24 eV/H2 and absorption capacity of 16 wt %, a record high value reported so far. The stability of the proposed metal-ethylene complexes was tested by extensive calculations such as normal-mode analysis, finite temperature firstprinciples moleculardynamics (MD) simulations, and reaction path calculations. The phonon and MD simulations indicate that the proposed structures are stable up to 500 K. The reaction path calculations indicate about 1 eV activation barrier for the TM 2 -ethylene complex to transform into a possible lower energy configuration where the ethylene molecule is dissociated. Importantly, no matter which isometric configuration the TM 2 -ethylene complex possesses, the TM atoms are able to bind multiple hydrogen molecules with suitable binding energy for room-temperature storage. These results suggest that codeposition of ethylene with a suitable precursor of TM or Li into nanopores of light-weight host materials may be a very promising route to discovering new materials with high-capacity hydrogen absorption properties. Recently, we have predicted ͓Phys. Rev. Lett. 97, 226102 ͑2006͔͒ that a single ethylene molecule can form stable complexes with light transition metals ͑TMs͒ such as Ti and the resulting TM n -ethylene complex can absorb up to ϳ12 and 14 wt % hydrogen for n = 1 and 2, respectively. Here we extend this study to include a large number of other metals and different isomeric structures. We obtained interesting results for light metals such as Li. The ethylene molecule is able to complex with two Li atoms with a binding energy of 0.7 eV/ Li which then binds up to two H 2 molecules per Li with a binding energy of 0.24 eV/ H 2 and absorption capacity of 16 wt %, a record high value reported so far. The stability of the proposed metal-ethylene complexes was tested by extensive calculations such as normal-mode analysis, finite temperature first-principles moleculardynamics ͑MD͒ simulations, and reaction path calculations. The phonon and MD simulations indicate that the proposed structures are stable up to 500 K. The reaction path calculations indicate about 1 eV activation barrier for the TM 2 -ethylene complex to transform into a possible lower energy configuration where the ethylene molecule is dissociated. Importantly, no matter which isometric configuration the TM 2 -ethylene complex possesses, the TM atoms are able to bind multiple hydrogen molecules with suitable binding ...

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“…6,7 Knowledge of the structures of metal-carbide clusters is important in understanding their potential applications. Despite this, many metal-carbide clusters still have unknown structures.…”

Section: Introductionmentioning

confidence: 99%

Onset of carbon–carbon bonding in the Nb₅C_y(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study

Dryza

Gascooke

Buntine

et al. 2009

Phys. Chem. Chem. Phys.

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. Onset of carbon-carbon bonding in the Nb5Cy (y = 0-6) clusters : a threshold photo-ionisation and density functional theory study. Physical Chemistry Chemical Physics, 11(7), 1060-1068. We have used photo-ionisation efficiency spectroscopy to determine the ionisation potentials (IPs) of the niobium-carbide clusters, Nb 5 C y (y = 0-6). Of these clusters Nb 5 C 2 and Nb 5 C 3 exhibit the lowest IPs. Complementary density functional theory calculations have been performed to locate the lowest energy isomers for each cluster. By comparing the experimental IPs with those calculated for candidate isomers, the structures of the Nb 5 C y clusters observed in the experiment are inferred. For all these structures, the underlying Nb 5 cluster has either a ''prolate'' or ''oblate'' trigonal bipyramid geometry. Both Nb 5 C 5 and Nb 5 C 6 are shown to contain carbon-carbon bonding in the form of one and two molecular C 2 units, respectively.

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Hydrogen storage capacity of titanium met-cars

Cited by 39 publications

References 29 publications

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

Hydrogen absorption properties of metal-ethylene complexes

Onset of carbon–carbon bonding in the Nb₅C_y(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study

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Hydrogen storage capacity of titanium met-cars

Cited by 39 publications

References 29 publications

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

Hydrogen absorption properties of metal-ethylene complexes

Onset of carbon–carbon bonding in the Nb5Cy(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study

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Onset of carbon–carbon bonding in the Nb₅C_y(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study