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Issue 23, 2018
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Hydrogenation properties of lithium and sodium hydride – closo-borate, [B10H10]2− and [B12H12]2−, composites

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Abstract

The hydrogen absorption properties of metal closo-borate/metal hydride composites, M2B10H10–8MH and M2B12H12–10MH, M = Li or Na, are studied under high hydrogen pressures to understand the formation mechanism of metal borohydrides. The hydrogen storage properties of the composites have been investigated by in situ synchrotron radiation powder X-ray diffraction at p(H2) = 400 bar and by ex situ hydrogen absorption measurements at p(H2) = 526 to 998 bar. The in situ experiments reveal the formation of crystalline intermediates before metal borohydrides (MBH4) are formed. On the contrary, the M2B12H12–10MH (M = Li and Na) systems show no formation of the metal borohydride at T = 400 °C and p(H2) = 537 to 970 bar. 11B MAS NMR of the M2B10H10–8MH composites reveal that the molar ratio of LiBH4 or NaBH4 and the remaining B species is 1 : 0.63 and 1 : 0.21, respectively. Solution and solid-state 11B NMR spectra reveal new intermediates with a B : H ratio close to 1 : 1. Our results indicate that the M2B10H10 (M = Li, Na) salts display a higher reactivity towards hydrogen in the presence of metal hydrides compared to the corresponding [B12H12]2− composites, which represents an important step towards understanding the factors that determine the stability and reversibility of high hydrogen capacity metal borohydrides for hydrogen storage.

Graphical abstract: Hydrogenation properties of lithium and sodium hydride – closo-borate, [B10H10]2− and [B12H12]2−, composites

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Publication details

The article was received on 17 Nov 2017, accepted on 24 May 2018 and first published on 04 Jun 2018


Article type: Paper
DOI: 10.1039/C7CP07776A
Citation: Phys. Chem. Chem. Phys., 2018,20, 16266-16275
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    Hydrogenation properties of lithium and sodium hydride – closo-borate, [B10H10]2− and [B12H12]2−, composites

    S. R. H. Jensen, M. Paskevicius, B. R. S. Hansen, A. S. Jakobsen, K. T. Møller, J. L. White, M. D. Allendorf, V. Stavila, J. Skibsted and T. R. Jensen, Phys. Chem. Chem. Phys., 2018, 20, 16266
    DOI: 10.1039/C7CP07776A

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