Issue 10, 2011

Reversibility of the hydrogen desorption from NaBH4 by confinement in nanoporous carbon

Abstract

NaBH4 is an interesting hydrogen storage material for mobile applications due to its high hydrogen content of 10.8 wt%. However, its practical use is hampered by the high temperatures (above 500 °C) required to release the hydrogen and by the non reversibility of the hydrogen sorption. In this study, we show that upon heating to 600 °C, bulk NaBH4 decomposed into Na and Na2B12H12, releasing the expected 8.1wt% of hydrogen. Nanosizing and confinement of NaBH4 in porous carbon resulted in much faster hydrogen desorption kinetics. The onset of hydrogen release was reduced from 470 °C for the bulk to below 250 °C for the nanocomposites. Furthermore, the dehydrogenated nanocomposites were partially rehydrogenated to form NaBH4, with the absorption of about 43% of the initial hydrogen capacity at relatively mild conditions (60 bar H2 and 325 °C). Reversibility in this system was limited due to partial loss of Na during dehydrogenation. The dehydrogenated boron compounds were almost fully rehydrogenated to NaBH4 (98%) when extra Na was added to the nanocomposites. To the best of our knowledge, this is the first time that reversibility for NaBH4 has been demonstrated.

Graphical abstract: Reversibility of the hydrogen desorption from NaBH4 by confinement in nanoporous carbon

Supplementary files

Article information

Article type
Paper
Submitted
17 Apr 2011
Accepted
08 Jul 2011
First published
08 Aug 2011

Energy Environ. Sci., 2011,4, 4108-4115

Reversibility of the hydrogen desorption from NaBH4 by confinement in nanoporous carbon

P. Ngene, R. van den Berg, M. H. W. Verkuijlen, K. P. de Jong and P. E. de Jongh, Energy Environ. Sci., 2011, 4, 4108 DOI: 10.1039/C1EE01481A

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