| Autor: |
Steffen R H, Jensen, Mark, Paskevicius, Bjarne R S, Hansen, Anders S, Jakobsen, Kasper T, Møller, James L, White, Mark D, Allendorf, Vitalie, Stavila, Jørgen, Skibsted, Torben R, Jensen |
| Rok vydání: |
2018 |
| Zdroj: |
Physical chemistry chemical physics : PCCP. 20(23) |
| ISSN: |
1463-9084 |
| Popis: |
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. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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