Nanoconfined LiBH4 and Enhanced Mobility of Li+聽and BH4鈥?/sup> Studied by Solid-State NMR

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• 作者：Margriet H. W. Verkuijlen ; Peter Ngene ; Daan W. de Kort ; Charlotte Barr茅 ; Angeloclaudio Nale ; Ernst R. H. van Eck ; P. Jan M. van Bentum ; Petra E. de Jongh ; Arno P. M. Kentgens
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：October 25, 2012
• 年：2012
• 卷：116
• 期：42
• 页码：22169-22178
• 全文大小：459K
• 年卷期：v.116,no.42(October 25, 2012)
• ISSN：1932-7455

文摘

The structural and dynamical properties of LiBH₄ confined in porous carbon and ordered porous silica are studied using ¹H, ⁷Li, and ¹¹B solid-state NMR. The ¹¹B and ⁷Li NMR resonances of LiBH₄ confined in porous carbon (broad pore size distribution up to <60 nm) are strongly broadened compared to bulk LiBH₄. This line broadening is dominated by anisotropic susceptibility effects induced by the nanostructured carbon host. Because of the lack of resolution caused by the anisotropic susceptibility broadening, we studied confined LiBH₄ in ordered porous silica (MCM-41 pore size: 1.9 nm). In the ⁷Li and ¹¹B spectra, a bulk-like LiBH₄ resonance is observed together with an additional, more narrow component. Above T = 313 K, this component showed a typical J-coupling pattern in both ¹¹B and ¹H spectra corresponding to highly mobile BH₄^{鈥?/sup> species. Static 11B solid-state NMR measurements compared with second moment calculations show that these BH₄鈥?/sup> species not only rotate as in the bulk material but also experience translations through the crystal lattice. Static 7Li measurements show that Li+ is also highly mobile. Therefore, we conclude that nanoconfinement of LiBH₄ strongly enhances diffusional mobility of borohydride anions and lithium in this material.}