Enhancement of the hydrogen release of Mg(BH4)2 by concomitant effects of nano-confinement and catalysis

Magnesium borohydride, Mg(BH4)2, is an interesting material for hydrogen storage due to its high hydrogen content (14.9 wt.% of H2). Unfortunately, a temperature of at least 350 °C is needed for releasing its hydrogen and the rehydrogenation process is only feasible under harsh conditions (950 bar H...

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Bibliographic Details
Published in:International journal of hydrogen energy 2019-02, Vol.44 (8), p.4253-4262
Main Authors: Clémençon, D., Davoisne, C., Chotard, J.-N., Janot, R.
Format: Article
Language:English
Subjects:
Activation energy
Chemical Sciences
Hydrogen storage
Inorganic chemistry
Magnesium borohydride
Material chemistry
Nano-catalyst
Nano-confinement
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Summary:Magnesium borohydride, Mg(BH4)2, is an interesting material for hydrogen storage due to its high hydrogen content (14.9 wt.% of H2). Unfortunately, a temperature of at least 350 °C is needed for releasing its hydrogen and the rehydrogenation process is only feasible under harsh conditions (950 bar H2 and 300 °C). In order to improve the performances of this compound, we analyze in this study the concomitant effects of nano-confinement into mesoporous carbons and addition of NiPt catalysts. This study uses different characterization tools to determine the effects of both nano-confinement and catalysts onto the pathway of decomposition. Usually, bulk Mg(BH4)2 decomposes in several steps passing through intermediate species for which activation energies are high. In this study, we show that the confinement and catalyst addition on Mg(BH4)2 result in a single step of hydrogen release and an activation energy below that of the bulk material with a value of 178 ± 14 kJ mol−1 as determined by the Kissinger's method. Interestingly, the hydrogen release is fully completed, i.e. 8H atoms per Mg(BH4)2 formula unit are released, in less than 2 h at 350 °C. •Magnesium borohydrides, Mg(BH4)2, as a high capacity hydrogen storage material.•NiPt core-hell nanoparticles as catalysts for hydrogen release.•A mesoporous carbon as confinement matrix for Mg(BH4)2.•A much lower activation energy for the hydrogen desorption process.•A full hydrogen release in less than 2 h at 350 °C.
ISSN:0360-3199
1879-3487
DOI:10.1016/j.ijhydene.2018.12.143