Combinatorial Search for Optimal Hydrogen-Storage Nanomaterials Based on Polymers

Lee, Hoonkyung; Choi, Woon Ih; Ihm, Jisoon

doi:10.1103/physrevlett.97.056104

Cited by 214 publications

(201 citation statements)

References 23 publications

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“…The OϪO separation on the same side is 5.1 Å, and the O/C ratio is 1:4. This coverage is close to a recent experimental report 15 31 we estimated the upper bound on the gravimetric H density at standard conditions to be 4.9 wt %. Note that the dihydride is too strongly bounded and is not considered in our estimation.…”

Section: Resultssupporting

confidence: 90%

Graphene Oxide as an Ideal Substrate for Hydrogen Storage

et al. 2009

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M olecular hydrogen (H 2 ) sorbents are appealing materials for storing hydrogen fuel onboard vehicles. The uptake and release of H 2 fuel in the sorbent materials can be fast and require less heat transfer. To use the H 2 sorbents at near ambient conditions, the binding energy of H 2 in these materials must be within certain range (e.g., 20Ϫ40 kJ/mol). 1,2 Theoretical studies predicted 3,4 that Kubaslike interactions between transition metal (TM) centers and coordinated H 2 could fall within this desirable energy range. Such predictions are consistent with recent experimental studies by using metalϪorganic frameworks (MOFs) with under-coordinated TM. 5Ϫ8 Attempts to anchor TM directly on carbon nanostructures, however, have not yet been successful. Recently, Hamaed et al. used organometallic precursor to successfully graft Ti onto the inner surface of mesoporous silica. 9 Though this work demonstrated the feasibility of individually dispersing Ti and the capability of binding multi-H 2 by dispersed Ti, mesoporous silica has a relatively small surface-to-volume ratio and may be too heavy for practical hydrogen storage. So far, no practical H 2 sorbent is available. Finding the right material for onboard storage is still a grand challenge. Concerning TM-based organometallic sorbents, several conditions are required at the same time: First, the substrate materials possess high surface-to-volume ratio and are lightweight. Second, the TM atoms are undercoordinated and well-exposed to accommodate multi-H 2 . Third, these unsaturated TM atoms, despite their high chemical reactivity, 10 do not form clusters. These require that the anchoring bonds between the TM atoms and the substrate are strong and the TM coverage is also optimized. Along the line of strengthening the anchoring bonds, several strategies have been suggested, such as functionalizing organic molecules, 11 employing defect sites in carbon materials, 12,13 and directly integrating metal atoms into the skeleton. 14,15 Alternatively, graphene oxide (GO) can be a potential substrate to covalently anchor TM atoms by simultaneously satisfying all these three conditions. GO has large surface-to-volume ratio and is intrinsically lightweight (condition 1). GO possesses ample O sites on the surfaces. Oxygen is the key in anchoring under-coordinated Ti (condition 2) and enhancing the TMϪ substrate binding (condition 3), as having been experimentally demonstrated on mesoporous silica. 9 Although GO has been routinely synthesized and extensively studied, 16Ϫ24 currently its precise atomic structures are still under intense investigation. In fact, the O content of GO can vary greatly, depending

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Section: Resultssupporting

confidence: 90%

Graphene Oxide as an Ideal Substrate for Hydrogen Storage

et al. 2009

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“…Examples of this approach fall into two categories: first, several groups have used DFT to evaluate the binding energies of hydrogen to functionalized fullerenes or other compounds. [127][128][129][130][131] While many promising compounds have been identified via this approach, realizing their synthesis has proven to be a challenge.…”

Section: Methods For Thermodynamic Assessmentmentioning

confidence: 99%

High capacity hydrogenstorage materials: attributes for automotive applications and techniques for materials discovery

et al. 2010

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Widespread adoption of hydrogen as a vehicular fuel depends critically upon the ability to store hydrogen on-board at high volumetric and gravimetric densities, as well as on the ability to extract/insert it at sufficiently rapid rates. As current storage methods based on physical means-high-pressure gas or (cryogenic) liquefaction-are unlikely to satisfy targets for performance and cost, a global research effort focusing on the development of chemical means for storing hydrogen in condensed phases has recently emerged. At present, no known material exhibits a combination of properties that would enable high-volume automotive applications. Thus new materials with improved performance, or new approaches to the synthesis and/or processing of existing materials, are highly desirable. In this critical review we provide a practical introduction to the field of hydrogen storage materials research, with an emphasis on (i) the properties necessary for a viable storage material, (ii) the computational and experimental techniques commonly employed in determining these attributes, and (iii) the classes of materials being pursued as candidate storage compounds. Starting from the general requirements of a fuel cell vehicle, we summarize how these requirements translate into desired characteristics for the hydrogen storage material. Key amongst these are: (a) high gravimetric and volumetric hydrogen density, (b) thermodynamics that allow for reversible hydrogen uptake/release under near-ambient conditions, and (c) fast reaction kinetics. To further illustrate these attributes, the four major classes of candidate storage materials-conventional metal hydrides, chemical hydrides, complex hydrides, and sorbent systems-are introduced and their respective performance and prospects for improvement in each of these areas is discussed. Finally, we review the most valuable experimental and computational techniques for determining these attributes, highlighting how an approach that couples computational modeling with experiments can significantly accelerate the discovery of novel storage materials (155 references).

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“…Recently, a novel concept to overcome these obstacles has been suggested [7][8][9][10][11][12][13][14]. It was predicted that a single Ti atom affixed to carbon nanostructures, such as C 60 or nanotubes, strongly adsorbs up to four hydrogen molecules [7,8,10].…”

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confidence: 99%

Transition-Metal-Ethylene Complexes as High-Capacity Hydrogen-Storage Media

et al. 2006

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From first-principles calculations, we predict that a single ethylene molecule can form a stable complex with two transition metals (TM) such as Ti. The resulting TM-ethylene complex then absorbs up to ten hydrogen molecules, reaching to gravimetric storage capacity of ∼14 wt%. Dimerization, polymerizations and incorporation of the TM-ethylene complexes in nanoporous carbon materials have been also discussed. Our results are quite remarkable and open a new approach to high-capacity hydrogen storage materials discovery.

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Combinatorial Search for Optimal Hydrogen-Storage Nanomaterials Based on Polymers

Cited by 214 publications

References 23 publications

Graphene Oxide as an Ideal Substrate for Hydrogen Storage

Graphene Oxide as an Ideal Substrate for Hydrogen Storage

High capacity hydrogenstorage materials: attributes for automotive applications and techniques for materials discovery

Transition-Metal-Ethylene Complexes as High-Capacity Hydrogen-Storage Media

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