Issue 4, 2014

NbN nanoparticles as additive for the high dehydrogenation properties of LiAlH4

Abstract

The effects of NbN nanoparticles synthesized via a simple “urea glass” route on the dehydrogenation properties of LiAlH4 have been systematically investigated. The particle size of the as-synthesized NbN nanoparticles is determined to be about 10 nm. The surface configuration and dehydrogenation behaviors of the 2 mol% NbN-doped LiAlH4 (2% NbN–LiAlH4) system are also discussed. It is found that the 2% NbN–LiAlH4 sample starts to decompose at about 95 °C and releases a total of 7.10 wt% hydrogen, which is 55 °C lower than that of as-milled LiAlH4. The isothermal dehydrogenation kinetics shows that the 2% NbN–LiAlH4 sample could release approximately 6.10 wt% hydrogen in 150 min at 130 °C, whereas as-received LiAlH4 only releases about 0.63 wt% hydrogen under the same conditions, revealing that the enhancements arising upon adding NbN nanoparticles are almost 8–9 times that of as-milled LiAlH4. The activation energy (Ea) is calculated to be 71.91 and 90.87 kJ mol−1 for the first and second hydrogen desorption of the NbN–LiAlH4 sample, a 38% and 32% reduction relative to as-received LiAlH4, respectively. A detailed modeling study shows that the first dehydrogenation step can be sufficiently interpreted with the nucleation and growth in a one-dimensional model based on the first-order reaction. More interestingly, the dehydrogenated LiAlH4 sample can recharge H2 under a 5.5 MPa hydrogen pressure. An SEM image of the dehydrogenated 8% NbN–LiAlH4 sample after HP-DSC under 5.5 MPa H2 shows that some nanorods appear.

Graphical abstract: NbN nanoparticles as additive for the high dehydrogenation properties of LiAlH4

Supplementary files

Article information

Article type
Paper
Submitted
23 Aug 2013
Accepted
15 Oct 2013
First published
16 Oct 2013

Dalton Trans., 2014,43, 1806-1813

NbN nanoparticles as additive for the high dehydrogenation properties of LiAlH4

L. Li, Y. Xu, Y. Wang, Y. Wang, F. Qiu, C. An, L. Jiao and H. Yuan, Dalton Trans., 2014, 43, 1806 DOI: 10.1039/C3DT52313F

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