Hydrogen in the mechanically prepared nanostructured graphite

Orimo, Shin Ichi; Majer, G.; Fukunaga, Toshiharu; Züttel, Andreas; Fujii, H.

doi:10.1063/1.125241

Cited by 234 publications

(190 citation statements)

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“…C nano H x is synthesized from graphite by the ball-milling under H 2 gas atmosphere. [13][14][15][16][17][18][19][20][21][22] So far, it has been reported that the hydrogenated nano-structural graphite (C nano H x ) can store about 7.4 mass% of hydrogen. 13 C nano H x material requires heating up to more than 700 C to release the hydrogen and desorbs hydrogen with hydrocarbons (CH 4 and C 2 H 6 ).…”

Section: Introductionmentioning

confidence: 99%

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Isobe

Yamada

Wang

et al. 2013

Journal of Applied Physics

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Li-C-H system, which can store about 5.0 mass% of rechargeable H 2 , has been reported as a promising hydrogen storage system by Ichikawa et al. [Appl. Phys. Lett. 86, 241914 (2005); Mater. Trans. 46, 1757Trans. 46, (2005]. This system was investigated from the thermodynamic and structural viewpoints. However, hydrogen absorption/desorption mechanism and the state of hydrogen atoms absorbed in the composite have not been clarified yet. In order to find new or better hydrogen storage system, graphite powder and nano-structural graphite ball-milled under H 2 and Ar atmosphere were prepared and milled with Li and Mg under Ar atmosphere in this study. Microstructural analysis for those samples by transmission electron microscope revealed that LiC 6 and/or LiC 12 were formed in Li-C-H system. On the other hand, MgC 2 was found in Mg-C-H system ball-milled under H 2 atmosphere, but not in the system ball-milled under Ar atmosphere. These results indicated that nano-structure in composites of nano-structural graphite is different from that of alkali (-earth) metal. For these reasons, metal-C-H system can be recognized to be a new family of hydrogen storage materials. V C 2013 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 99%

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Isobe

Yamada

Wang

et al. 2013

Journal of Applied Physics

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“…However, it has been experimentally confirmed that the maximum hydrogen concentration is 7 mass% in milled graphite. [12][13][14][15][16] This indicates that the amount of the hydrocarbon components in the thermally desorbed gases is abundant for nanostructural graphite milled by the rocking mill method because the hydrogen content does not depend on the milling method. From these results, it is concluded that the hydrogenated state in the nanostructural graphite is considerably affected by the milling conditions as well.…”

Section: Resultsmentioning

confidence: 98%

“…[12][13][14][15][16] However, higher temperature than 700 C is necessary to release all of the chemisorbed hydrogen from C nano H x , because the covalent bond between C and H is too strong to desorb hydrogen. 17) In this paper, we report on the issues how to destabilize the Li-H and C-H bonds.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Desorption Properties of Lithium–Carbon–Hydrogen System

2005

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Hydrogen desorption properties of a mixture of hydrogenated nanostructural graphite C nano H x and lithium hydride LiH are demonstrated in this paper, where C nano H x was synthesized from graphite by ballmilling under 1 MPa hydrogen for 80 h. First of all, we clarified the hydrogenated properties of C nano H x synthesized under four different milling conditions. The hydrogen desorption profile with typical two-peak structure was caused by iron contamination in C nano H x from steel balls during ballmilling, while the products prepared by zirconia balls showed the broad single peak in hydrogen desorption. The amount of desorbed hydrocarbon gas from the products using a rocking (vibrating) mill estimated by the thermogravimetry was larger than that using a rotating (planetary) one. Next, the destabilization properties of extremely stable LiH was examined, indicating that LiH was destabilized by mixing with another component LiOH or NaOH, and then, the mixture easily released hydrogen gas at lower temperature compared with LiH, LiOH and NaOH themselves. On the analogy of this result, we examined hydrogen desorption properties of the ballmilled mixture of LiH and C nano H x . The hydrogen desorption started from about 200 C and showed a peak at 350 C, although each product needs more than 400 C to release hydrogen. Since this hydrogen storage system is specially based on lithium, carbon and hydrogen in the mixture, it can be regarded as Li-C-H hydrogen storage system.

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“…One possible area might be hydrogen storage, since forms of carbon rather similar to those described here have been shown to have H 2 storage capabilities. Thus, Orimo et al reported in 1999 that "nanostructured graphite" prepared by mechanical milling of synthetic graphite can have high H 2 uptakes [25]. Carbon nanohorns have also been shown to have potentially useful H 2 storage properties [26].…”

Section: Discussionmentioning

confidence: 99%

Structural transformation of graphite by arc-discharge

Harris

2011

Philosophical Magazine

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International audienceThe formation of novel structures by the passage of an electric current through graphite is described. These structures apparently consist of hollow three-dimensional graphitic shells bounded by curved and faceted planes, typically made up of two graphene layers. The curved structures were frequently decorated with nano-scale carbon particles, or short nanotubes. In some cases, nanotubes were found to be seamlessly connected to the thin shells, indicating that the formation of the shells and the nanotubes is intimately connected. Small nanotubes or nanoparticles were also sometimes found encapsulated inside the hollow structures, while fullerene-like particles were often seen attached to the outside surfaces. With their high surface areas and structural perfection, the new carbon structures may have applications as anodes of lithium ion batteries or as components of composite materials

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Hydrogen in the mechanically prepared nanostructured graphite

Abstract: Hydrogen trapping state associated with the low temperature thermal desorption spectroscopy peak in hydrogenated nanostructured graphite J. Appl. Phys.

Cited by 234 publications

References 19 publications

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Hydrogen Desorption Properties of Lithium–Carbon–Hydrogen System

Structural transformation of graphite by arc-discharge

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Hydrogen in the mechanically prepared nanostructured graphite

Abstract: Hydrogen trapping state associated with the low temperature thermal desorption spectroscopy peak in hydrogenated nanostructured graphite J. Appl. Phys.

Cited by 234 publications

References 19 publications

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Microscopic characterization of metal-carbon-hydrogen composites (metal = Li, Mg)

Hydrogen Desorption Properties of Lithium&ndash;Carbon&ndash;Hydrogen System

Structural transformation of graphite by arc-discharge

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Hydrogen Desorption Properties of Lithium–Carbon–Hydrogen System