A New Ammine Dual‐Cation (Li,Mg) Borohydride: Synthesis,Structure, and Dehydrogenation Enhancement |
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| Authors: | Dr. Weiwei Sun Xiaowei Chen Dr. Qinfen Gu Kia S. Wallwork Yingbin Tan Ziwei Tang Prof. Xuebin Yu |
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| Affiliation: | 1. Department of Materials Science, Fudan University, Shanghai 200433 (P.R. China);2. Australian Synchrotron, 800 Blackburn Rd, Clayton 3168 (Australia) |
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| Abstract: | A new ammine dual‐cation borohydride, LiMg(BH4)3(NH3)2, has been successfully synthesized simply by ball‐milling of Mg(BH4)2 and LiBH4 ? NH3. Structure analysis of the synthesized LiMg(BH4)3(NH3)2 revealed that it crystallized in the space group P63 (no. 173) with lattice parameters of a=b=8.0002(1) Å, c=8.4276(1) Å, α=β=90°, and γ=120° at 50 °C. A three‐dimensional architecture is built up through corner‐connecting BH4 units. Strong N? H???H? B dihydrogen bonds exist between the NH3 and BH4 units, enabling LiMg(BH4)3(NH3)2 to undergo dehydrogenation at a much lower temperature. Dehydrogenation studies have revealed that the LiMg(BH4)3(NH3)2/LiBH4 composite is able to release over 8 wt % hydrogen below 200 °C, which is comparable to that released by Mg(BH4)3(NH3)2. More importantly, it was found that release of the byproduct NH3 in this system can be completely suppressed by adjusting the ratio of Mg(BH4)2 and LiBH4 ? NH3. This chemical control route highlights a potential method for modifying the dehydrogenation properties of other ammine borohydride systems. |
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| Keywords: | ammine borohydrides dehydrogenation dual‐cation compounds hydrogen X‐ray diffraction |
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