Functionalized Porous Silicas with Unsaturated Early Transition Metal Moieties as Hydrogen Storage Materials: Comparison of Metal and Oxidation State

Hamaed, Ahmad; Hung, V.; Hoang, Tuan K.A.; Antonelli, David M.

doi:10.1021/jp1013048

Cited by 18 publications

(19 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several H 2 molecules can cluster onto a single metal atom through this type of orbital interactions. Numerous theorists explored the transition metaldecorated surface structures as a hydrogen storage medium (47)(48)(49), and experimentalists identified the Kubas-type hydrogen molecular adsorptions onto such sites of adsorption (50)(51)(52)(53).…”

Section: Transition Metal and Kubas Interactionmentioning

confidence: 99%

Progress on first-principles-based materials design for hydrogen storage

Park

Choi

Hwang

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

This article briefly summarizes the research activities in the field of hydrogen storage in sorbent materials and reports our recent works and future directions for the design of such materials. Distinct features of sorption-based hydrogen storage methods are described compared with metal hydrides and complex chemical hydrides. We classify the studies of hydrogen sorbent materials in terms of two key technical issues: (i) constructing stable framework structures with high porosity, and (ii) increasing the binding affinity of hydrogen molecules to surfaces beyond the usual van der Waals interaction. The recent development of reticular chemistry is summarized as a means for addressing the first issue. Theoretical studies focus mainly on the second issue and can be grouped into three classes according to the underlying interaction mechanism: electrostatic interactions based on alkaline cations, Kubas interactions with open transition metals, and orbital interactions involving Ca and other nontransitional metals. Hierarchical computational methods to enable the theoretical predictions are explained, from ab initio studies to molecular dynamics simulations using force field parameters. We also discuss the actual delivery amount of stored hydrogen, which depends on the charging and discharging conditions. The usefulness and practical significance of the hydrogen spillover mechanism in increasing the storage capacity are presented as well. Renewable Energy and the Significance of Hydrogen StorageT he prosperity of modern civilization is inextricably based on energy supply networks (on-grid or off-grid) that deliver petroleum, natural gas, and electricity to residential, public, commercial, and industrial facilities, as well as transport systems. Concerns are growing over the limited availability of natural resources and the environmentally hazardous byproducts of the energy conversion process, such as greenhouse gases. From this perspective, renewable energy harvesting technologies based on natural energy flows, including solar power, wind power, geothermal energy, and tidal energy, are increasingly gaining momentum. The storage of the harvested energy remains a fundamentally important factor for the utilization of the renewable energy because the sources of the renewable energy usually undergo significant spatial and temporal variations (1). The issue of hydrogen storage can be understood in this context. Among chemical fuels, pure hydrogen (i.e., in the gas form) has the highest mass density but the poorest volumetric density (2, 3). As a result, hydrogen storage research traces a long history of studies toward the reversible condensation of hydrogen into a limited volume using lightweight devices. In recent decades a globally recognized objective is the development of a stored hydrogen carrier that can power vehicles through fuel cells (or, perhaps, combustion engines). For example, the guideline published by the US Department of Energy states that, for a commercially competitive vehicle, hydrogen storage systems ne...

show abstract

Section: Transition Metal and Kubas Interactionmentioning

confidence: 99%

Progress on first-principles-based materials design for hydrogen storage

Park

Choi

Hwang

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…This is similar to the synergic bonding described by the Dewar-Chatt-Duncanson model for the interaction of, for example, CO with transition metals. [10,11] We have previously investigated, both experimentally and computationally, mesoporous amorphous silica-based materials with benzyl titanium H 2 binding sites, [12,13] and have shown computationally that the Kubas interaction is present in these systems. Since these are only model systems with no practical value due to the low concentration of effective binding sites, our recent experimental research has focused on materials consisting of extended networks of metal fragments bound together by hydrazine, in which the hydrogen is once again thought to bind to the metal centres through a Kubas interaction.…”

Section: Introductionmentioning

confidence: 99%

Transition Metal Hydrazide‐Based Hydrogen‐Storage Materials: the First Atoms‐In‐Molecules Analysis of the Kubas Interaction

Skipper

Hoang

Antonelli

et al. 2012

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Molecular models of the M-H(2) binding sites of experimentally characterised amorphous vanadium hydrazide gels are studied computationally using gradient corrected density functional theory, to probe the coordination number of the vanadium in the material and the nature of the interaction between the metal and the H(2) molecules. The H(2) is found to bind to the vanadium through the Kubas interaction, and the first quantum theory of atoms-in-molecules analysis of this type of interaction is reported. Strong correlation is observed between the electron density at the H-H bond critical point and the M-H(2) interaction energy. Four coordinate models give the best reproduction of the experimental data, suggesting that the experimental sites are four coordinate. The V-H(2) interaction is shown to be greater when the non-hydrazine based ligand, THF, of the experimental system is altered to a poorer π-acceptor ligand. Upon altering the metal to Ti or Cr the M-H(2) interaction energy changes little but the number of H(2) which may be bound decreases from four (Ti) to two (Cr). It is proposed that changing the metal from V to Ti may increase the hydrogen storage capacity of the experimental system. A 9.9 wt% maximum storage capacity at the ideal binding enthalpy for room temperature performance is predicted when the Ti metal is combined with a coordination sphere containing 2 hydride ligands.

show abstract

“…2,[11][12][13][14][15][16][17] Our first computational study was of a storage material based on an experimentally confirmed mesoporous silicate with titanium benzyl binding sites, 11 and the second was a hydrazine linked system containing vanadium binding sites. 2,[11][12][13][14][15][16][17] Our first computational study was of a storage material based on an experimentally confirmed mesoporous silicate with titanium benzyl binding sites, 11 and the second was a hydrazine linked system containing vanadium binding sites.…”

Section: Introductionmentioning

confidence: 99%

The Kubas interaction in M(ii) (M = Ti, V, Cr) hydrazine-based hydrogen storage materials: a DFT study

et al. 2012

Self Cite

View full text Add to dashboard Cite

The Cr(II) binding sites of an experimentally realised hydrazine linked hydrogen storage material have been studied computationally using density functional theory. Both the experimentally determined rise in H(2) binding enthalpy upon alteration of the ancillary ligand from bis[(trimethylsilyl)methyl] to hydride, and the number of H(2) molecules per Cr centre, are reproduced reasonably well. Comparison with analogous Ti(II), V(II) and Mn(II) systems suggests that future experiments should focus on the earliest 3d metals, and also suggests that 5 and 7 wt% H(2) storage may be possible for V(II) and Ti(II) respectively. Alteration of the metal does not have a large effect on the M-H(2) interaction energy, while alteration of the ancillary ligand bound to the metal centre, from bis[(trimethylsilyl)methyl] or hydride to two hydride ligands, THF and only hydrazine based ligands, indicates that ancillary ligands that are poor π-acceptors give stronger M-H(2) interactions. Good evidence is found that the M-H(2) interaction is Kubas type. Orbitals showing σ-donation from H(2) to the metal and π-back-donation from the metal to the dihydrogen are identified, and atoms-in-molecules analysis indicates that the electron density at the bond critical points of the bound H(2) is similar to that of classical Kubas systems. The Kubas interaction is dominated by σ-donation from the H(2) to the metal for Cr(II), but is more balanced between σ-donation and π-back-donation for the Ti(II) and V(II) analogues. This difference in behaviour is traced to a lowering in energy of the metal 3d orbitals across the transition series.

show abstract

Functionalized Porous Silicas with Unsaturated Early Transition Metal Moieties as Hydrogen Storage Materials: Comparison of Metal and Oxidation State

Cited by 18 publications

References 39 publications

Progress on first-principles-based materials design for hydrogen storage

Progress on first-principles-based materials design for hydrogen storage

Transition Metal Hydrazide‐Based Hydrogen‐Storage Materials: the First Atoms‐In‐Molecules Analysis of the Kubas Interaction

The Kubas interaction in M(ii) (M = Ti, V, Cr) hydrazine-based hydrogen storage materials: a DFT study

Contact Info

Product

Resources

About