Hydrogen storage: the remaining scientific and technological challenges

Felderhoff, Michael; Weidenthaler, Claudia; Helmolt, R. von; Eberle, Ulrich

doi:10.1039/b701563c

Cited by 470 publications

(301 citation statements)

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“…Our results demonstrate that H 2 storage in metal-doped carbon substrates can be severely affected by hitherto unexplored quantummechanical effects. The efficient storage of hydrogen represents an important prerequisite for a sustainable, low-CO 2 economy [1]. Owing to their light weight and large surface areas, carbonbased nanostructured materials (CNMs) have been extensively studied as candidates to meet the US-DOE 2010 target of 6.5 wt % [1,2].…”

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confidence: 99%

“…The efficient storage of hydrogen represents an important prerequisite for a sustainable, low-CO 2 economy [1]. Owing to their light weight and large surface areas, carbonbased nanostructured materials (CNMs) have been extensively studied as candidates to meet the US-DOE 2010 target of 6.5 wt % [1,2]. To date, however, no carbon host has been found to meet such stringent requirements.…”

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confidence: 99%

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Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

et al. 2008

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The adsorption of molecular hydrogen (H 2 ) in the graphite intercalation compound KC 24 is studied both experimentally and theoretically. High-resolution inelastic neutron data show spectral features consistent with a strong pinning of H 2 along a single axis. First-principles calculations provide novel insight into the nature of H 2 binding in intercalates but fail to account for the symmetry of the H 2 orientational potential deduced from experiment. The above discrepancy disappears once the H 2 center of mass is allowed to delocalize in the quantum-mechanical sense across three vicinal adsorption sites, naturally leading to the well-known saturation coverage of $2H 2 per metal atom in this material. Our results demonstrate that H 2 storage in metal-doped carbon substrates can be severely affected by hitherto unexplored quantummechanical effects. [12,13] and CsC 24 [14] has been investigated by inelastic neutron scattering (INS). INS features were attributed to the presence of two distinct adsorption sites. Our recent work on KC 24 ðH 2 Þ x shows no preferential site occupancy for x ¼ 1:0 and 1.5 [15,16], where x represents the amount of adsorbed H 2 . This finding strongly suggests the existence of a single adsorption site in KC 24 , making it a superb candidate for more detailed studies. The aim of this Letter is to probe the H 2 -KC 24 potential energy landscape via a detailed analysis of high-resolution INS data. The experimental results are supplemented by plane-wave densityfunctional-theory (PW-DFT) calculations so as to provide novel insight into the nature of H 2 -GIC complexes.High-purity KC 24 was synthesized from nuclear-grade Papyex [17] using a modified one-zone method with a 20 wt % stoichiometric K excess at 300 C [16]. The sample was annealed for 3 days until the appearance of a uniform blue color signaling charge transfer from the alkali to graphite, and then stored under argon. Neutron measurements were carried out under in situ H 2 loading on the IRIS [18] and TOSCA [19] spectrometers. Data were collected at 1.5 K (IRIS) and 12.5 K (TOSCA) for x ¼ 0, 0.25, 0.5, 1.0, and 2.0, as measured volumetrically during dosing. An additional over-saturation concentration of x ¼ 6:25 was measured on IRIS only. The x ¼ 0 data were used as background spectrum for subsequent subtraction.Figure 1(a) shows the dependence of the (003) Bragg reflection with x. These data were collected following the relaxation of normal-H 2 to the para ground state over a period of several hours. The intensity of the KC 24 peak at 2.90 Å diminishes with x while a second feature appears above 2.97 Å , with its peak maximum shifting steadily towards higher d-spacings up to x ¼ 2:0. Both peaks remain discrete and coexist at all explored x, indicating the PRL 101, 126101 (2008)

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Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

et al. 2008

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“…(r, R, θ ), (1) where E B + −H 2 (r, R, θ ) is the total molecular energy, while E DCBS B + (r, R, θ ) and E DCBS H 2 (r, R, θ ) are the total monomer energies of B + or H 2 calculated in the basis set of all bodiesthe dimer centered basis set (DCBS). This form for the interaction energy explicitly corrects the basis set superposition error using the standard counter-poise correction scheme.…”

Section: Potential Energy Surface For B + -Hmentioning

confidence: 99%

“…[1][2][3][4][5] Chemists are developing these materials to reversibly bind and store hydrogen in a form that is safer than compressed H 2 gas and which can be used for mobile applications. To optimise these materials it is crucial to understand the nature of the M + · · ·H 2 interaction.…”

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Properties of the B+-H2 and B+-D2 complexes: A theoretical and spectroscopic study

Poad

Dryza

Buchachenko

et al. 2012

The Journal of Chemical Physics

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The rotationally resolved infrared spectrum of the B+-D2 ion-neutral complex is recorded in the D-D stretch vibration region (2805-2875 cm−1) by detecting B+ photofragments. Analysis of the spectrum confirms a Tshaped equilibrium geometry for the B+-D2 complex with a vibrationally averaged intermolecular bond length of 2.247 Å, around 0.02 Å shorter than for the previously characterised B+-H2 complex [V. Dryza, B. L. J. Poad, and E. J. Bieske, J. Am. Chem. Soc. 130, 12986 (2008)10.1021/ja8018302]. The D-D stretch band centre occurs at 2839.76 ± 0.10 cm−1, representing a −153.8 cm−1 shift from the Q1(0) transition of the free D2 molecule. A new three dimensional ab initio potential energy surface for the B++H2 interaction is calculated using the coupled cluster RCCSD(T) method and is used in variational calculations for the rovibrational energies of B+-H2 and B+-D2. The calculations predict dissociation energies of 1254 cm−1 for B+-H2 with respect to the B++H2 (j = 0) limit, and 1313 cm−1 for B+-D2 with respect to the B++D2 (j = 0) limit. The theoretical approach reproduces the rotational and centrifugal constants of the B+-H2 and B+-D2 complexes to within 3%, and the magnitude of the contraction of the intermolecular bond accompanying excitation of the H2 or D2 sub-unit, but underestimates the H-H and D-D vibrational band shifts by 7%-8%. Combining the theoretical and experimental results allows a new, more accurate estimation for the B+-H2 band origin (3939.64 ± 0.10 cm−1).

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“…2 Most effective in improving the performance of metal hydrides are reducing the particle size to the nm range (typically below 30 nm) 3-13 or adding one or more promoters/catalysts to bulk materials. [14][15][16][17][18][19][20][21][22][23][24][25] …”

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Towards a structure-performance relationship for hydrogen storage in Ti-doped NaAlH₄nanoparticles

et al. 2011

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Hydrogen storage properties of Ti-doped nanosized (B20 nm) NaAlH 4 supported on carbon nanofibers were affected by the stage at which Ti was introduced. When Ti was deposited first followed by NaAlH 4, sorption properties were superior to the case where NaAlH 4 was deposited first followed by NaAlH 4 . This was the result of both a smaller NaAlH 4 particle size and the more extensive catalytic action of Ti in the former material.Sodium alanate has become a show-case for research on lightweight complex metal hydrides for hydrogen storage. 1 Nevertheless, hydrogen release rates and absorption rates are often impeded in metal hydrides and need to be improved. 2 Most effective in improving the performance of metal hydrides are reducing the particle size to the nm range (typically below 30 nm) 3-13 or adding one or more promoters/catalysts to bulk materials. [14][15][16][17][18][19][20][21][22][23][24][25]

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Hydrogen storage: the remaining scientific and technological challenges

Cited by 470 publications

References 69 publications

Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

Properties of the B+-H2 and B+-D2 complexes: A theoretical and spectroscopic study

Towards a structure-performance relationship for hydrogen storage in Ti-doped NaAlH₄nanoparticles

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Hydrogen storage: the remaining scientific and technological challenges

Cited by 470 publications

References 69 publications

Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

Quantum Delocalization of Molecular Hydrogen in Alkali-Graphite Intercalates

Properties of the B+-H2 and B+-D2 complexes: A theoretical and spectroscopic study

Towards a structure-performance relationship for hydrogen storage in Ti-doped NaAlH4nanoparticles

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Towards a structure-performance relationship for hydrogen storage in Ti-doped NaAlH₄nanoparticles