Energies (Aug 2015)

Increasing Hydrogen Density with the Cation-Anion Pair BH4−-NH4+ in Perovskite-Type NH4Ca(BH4)3

  • Pascal Schouwink,
  • Fabrice Morelle,
  • Yolanda Sadikin,
  • Yaroslav Filinchuk,
  • Radovan Černý

DOI
https://doi.org/10.3390/en8088286
Journal volume & issue
Vol. 8, no. 8
pp. 8286 – 8299

Abstract

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A novel metal borohydride ammonia-borane complex Ca(BH4)2·NH3BH3 is characterized as the decomposition product of the recently reported perovskite-type metal borohydride NH4Ca(BH4)3, suggesting that ammonium-based metal borohydrides release hydrogen gas via ammonia-borane-complexes. For the first time the concept of proton-hydride interactions to promote hydrogen release is applied to a cation-anion pair in a complex metal hydride. NH4Ca(BH4)3 is prepared mechanochemically from Ca(BH4)2 and NH4Cl as well as NH4BH4 following two different protocols, where the synthesis procedures are modified in the latter to solvent-based ball-milling using diethyl ether to maximize the phase yield in chlorine-free samples. During decomposition of NH4Ca(BH4)3 pure H2 is released, prior to the decomposition of the complex to its constituents. As opposed to a previously reported adduct between Ca(BH4)2 and NH3BH3, the present complex is described as NH3BH3-stuffed α-Ca(BH4)2.

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