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Interface effects in NaAlH4–carbon nanocomposites for hydrogen storage

Gao, Jinbao and Ngene, Peter and Herrich, Monika and Xia, Wei and Gutfleisch, Oliver and Muhler, Martin and de Jong, Krijn P. and de Jongh, Petra E. (2014):
Interface effects in NaAlH4–carbon nanocomposites for hydrogen storage.
In: International Journal of Hydrogen Energy, Elsevier Science Publishing, pp. 10175-10183, 39, (19), ISSN 03603199,
[Online-Edition: http://dx.doi.org/10.1016/j.ijhydene.2014.03.188],
[Article]

Abstract

For practical solid-state hydrogen storage, reversibility under mild conditions is crucial. Complex metal hydrides such as NaAlH4 and LiBH4 have attractive hydrogen contents. However, hydrogen release and especially uptake after desorption are sluggish and require high temperatures and pressures. Kinetics can be greatly enhanced by nanostructuring, for instance by confining metal hydrides in a porous carbon scaffold. We present for a detailed study of the impact of the nature of the carbon–metal hydride interface on the hydrogen storage properties. Nanostructures were prepared by melt infiltration of either NaAlH4 or LiBH4 into a carbon scaffold, of which the surface had been modified, varying from H-terminated to oxidized (up to 4.4 O/nm2). It has been suggested that the chemical and electronic properties of the carbon/metal hydride interface can have a large influence on hydrogen storage properties. However, no significant impact on the first H2 release temperatures was found. In contrast, the surface properties of the carbon played a major role in determining the reversible hydrogen storage capacity. Only a part of the oxygen-containing groups reacted with hydrides during melt infiltration, but further reaction during cycling led to significant losses, with reversible hydrogen storage capacity loss up to 40% for surface oxidized carbon. However, if the carbon surface had been hydrogen terminated, ∼6 wt% with respect to the NaAlH4 weight was released in the second cycle, corresponding to 95% reversibility. This clearly shows that control over the nature and amount of surface groups offers a strategy to achieve fully reversible hydrogen storage in complex metal hydride-carbon nanocomposites.

Item Type: Article
Erschienen: 2014
Creators: Gao, Jinbao and Ngene, Peter and Herrich, Monika and Xia, Wei and Gutfleisch, Oliver and Muhler, Martin and de Jong, Krijn P. and de Jongh, Petra E.
Title: Interface effects in NaAlH4–carbon nanocomposites for hydrogen storage
Language: English
Abstract:

For practical solid-state hydrogen storage, reversibility under mild conditions is crucial. Complex metal hydrides such as NaAlH4 and LiBH4 have attractive hydrogen contents. However, hydrogen release and especially uptake after desorption are sluggish and require high temperatures and pressures. Kinetics can be greatly enhanced by nanostructuring, for instance by confining metal hydrides in a porous carbon scaffold. We present for a detailed study of the impact of the nature of the carbon–metal hydride interface on the hydrogen storage properties. Nanostructures were prepared by melt infiltration of either NaAlH4 or LiBH4 into a carbon scaffold, of which the surface had been modified, varying from H-terminated to oxidized (up to 4.4 O/nm2). It has been suggested that the chemical and electronic properties of the carbon/metal hydride interface can have a large influence on hydrogen storage properties. However, no significant impact on the first H2 release temperatures was found. In contrast, the surface properties of the carbon played a major role in determining the reversible hydrogen storage capacity. Only a part of the oxygen-containing groups reacted with hydrides during melt infiltration, but further reaction during cycling led to significant losses, with reversible hydrogen storage capacity loss up to 40% for surface oxidized carbon. However, if the carbon surface had been hydrogen terminated, ∼6 wt% with respect to the NaAlH4 weight was released in the second cycle, corresponding to 95% reversibility. This clearly shows that control over the nature and amount of surface groups offers a strategy to achieve fully reversible hydrogen storage in complex metal hydride-carbon nanocomposites.

Journal or Publication Title: International Journal of Hydrogen Energy
Volume: 39
Number: 19
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Hydrogen storage, Complex metal hydrides, Porous matrix, Carbon, Surface modification, Reversibility
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Nov 2014 09:28
Official URL: http://dx.doi.org/10.1016/j.ijhydene.2014.03.188
Identification Number: doi:10.1016/j.ijhydene.2014.03.188
Funders: We thank Timcal Ltd., Bodio, Switzerland, for providing the high surface area graphite., This work was financially supported by NWO-ACTS-Sustainable Hydrogen and an NWO-Vidi grant (016.072.316).
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