Fabrication and hydrogen sorption behaviour of nanoparticulate MgH_2 incorporated in a porous carbon host
Abstract
Nanoparticles of MgH_2 incorporated in a mesoporous carbon aerogel demonstrated accelerated hydrogen exchange kinetics but no thermodynamic change in the equilibrium hydrogen pressure. Aerogels contained pores from <2 to ~30 nm in diameter with a peak at 13 nm in the pore size distribution. Nanoscale MgH_2 was fabricated by depositing wetting layers of nickel or copper on the aerogel surface, melting Mg into the aerogel, and hydrogenating the Mg to MgH_2. Aerogels with metal wetting layers incorporated 9–16 wt% MgH_2, while a metal free aerogel incorporated only 3.6 wt% MgH_2. The improved hydrogen sorption kinetics are due to both the aerogel limiting the maximum MgH_2 particle diameter and a catalytic effect from the Ni and Cu wetting layers. At 250 °C, MgH_2 filled Ni decorated and Cu decorated carbon aerogels released H_2 at 25 wt% h^−1 and 5.5 wt% h^−1, respectively, while a MgH_2 filled aerogel without catalyst desorbed only 2.2 wt% h^−1 (all wt% h^−1 values are with respect to MgH_2 mass). At the same temperature, MgH_2 ball milled with synthetic graphite desorbed only 0.12 wt% h^−1, which demonstrated the advantage of incorporating nanoparticles in a porous host.
Additional Information
© 2009 IOP Publishing. Received 29 September 2008, in final form 27 October 2008. Published 23 April 2009. We thank the US Department of Energy (DOE contract DEFC36- 05GO15067) for support of this work. One of us (CCA) would like to acknowledge DoE through contract DE-FC36- 05GO15065. TEM work benefited from use of the Caltech KNI and Mat Sci TEM facilities supported by the MRSEC Programme of the National Science Foundation under Award Number DMR-0520565.Additional details
- Eprint ID
- 14986
- Resolver ID
- CaltechAUTHORS:20090812-105527043
- Department of Energy (DOE)
- DE-FC36-05GO15067
- Department of Energy (DOE)
- DE-FC36-05GO15065
- NSF
- DMR-0520565
- Created
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2009-08-12Created from EPrint's datestamp field
- Updated
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2022-07-12Created from EPrint's last_modified field
- Caltech groups
- Kavli Nanoscience Institute