Role of Amino Anion in Metal Amides/Imides for Hydrogen Storage: A First Principle Study
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- 作者：Qiang Wang ; Yungui Chen ; Jinggang Gai ; Chaoling Wu ; Mingda Tao
- 刊名：Journal of Physical Chemistry C
- 出版年：2008
- 出版时间：November 20, 2008
- 年：2008
- 卷：112
- 期：46
- 页码：18264-18269
- 全文大小：189K
- 年卷期：v.112,no.46(November 20, 2008)
- ISSN：1932-7455
文摘
For favorable thermodynamics and the considerable kinetics of the hydrogen reaction, Li−Mg−N−H compounds hold promise as novel hydrogen storage materials for on-board usage in metal amide hydrogen storage systems. To improve their performance, much effort has been devoted to the fundamental properties of metal amides, such as electronic structure, and the energetics of their hydrogen reactions. Though understanding the amino anion transition in the hydrogen reaction is essential for further development, the role of the amino anion in metal amides/imides for hydrogen storage is still ambiguous. In this study, we investigated the electronic structures and chemical bonds of Mg(NH2)2, LiNH2, and Li2MgN2H2 by way of a first principle approach. Then, the H vacancy formation energies in LiNH2 and Li2MgN2H2 were estimated to comprehend the stability of the amino anion in metal amides/imides and its effect on the thermodynamics of the hydrogen reaction. Also, the transformation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in LiNH2 and Li2MgN2H2 was calculated for a deeper understanding of the chemical interaction of the (2LiNH2 + MgH2) dehydriding reaction. Last, but not least, special attention is devoted to the calculation of the energetics of this reaction and its rehydrogenation.