2LiBH₄-MgH₂-0.13TiCl₄ confined in nanoporous structure of carbon aerogel scaffold for reversible hydrogen storage

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• 作者：Rapee Gosalawit-Utke^a ; ^b ; ^{rapee.g@sut.ac.th" class="auth_mail} ; Chiara Milanese^c ; Payam Javadian^d ; Alessandro Girella^c ; Daniel Laipple^a ; Juliá ; n Puszkiel^a ; Alice S. Cattaneo^e ; Chiara Ferrara^e ; Jatuporn Wittayakhun^b ; Jø ; rgen Skibsted^d ; Torben R. Jensen^d ; Amedeo Marini^c ; Thomas Klassen^a ; Martin Dornheim^a
• 关键词：Nanoconfinement ; Eutectic LiBH4&ndash ; Mg(BH4)2 ; Magnesium borohydride ; TiCl4 ; Lithium&ndash ; titanium borohydride
• 刊名：Journal of Alloys and Compounds
• 出版年：25 June, 2014
• 年：2014
• 卷：599
• 期：Complete
• 页码：78-86
• 全文大小：3442 K

文摘

The investigations based on kinetic improvement and reaction mechanisms during melt infiltration, dehydrogenation, and rehydrogenation of nanoconfined 2LiBH₄-MgH₂-0.13TiCl₄ in carbon aerogel scaffold (CAS) are proposed. It is found that TiCl₄ and LiBH₄ are successfully nanoconfined in CAS, while MgH₂ proceeds partially. In the same temperature (25-500 掳C) and time (0-5 h at constant temperature) ranges nanoconfined 2LiBH₄-MgH₂-0.13TiCl₄ dehydrogenates completely 99% of theoretical H₂ storage capacity, while that of nanoconfined 2LiBH₄-MgH₂ is only 94%. Nanoconfined 2LiBH₄-MgH₂-0.13TiCl₄ performs three-step dehydrogenation at 140, 240, and 380 掳C. Onset (the first-step) dehydrogenation temperature (140 掳C), significantly lower than those of nanoconfined sample of 2LiBH₄-MgH₂ and 2LiBH₄-MgH₂-TiCl₃ (螖T = 140 and 110 掳C, respectively) is in agreement with the decomposition of eutectic LiBH₄-Mg(BH₄)₂ and lithium-titanium borohydride. For the second and third steps (240 and 380 掳C), decompositions of LiBH₄ destabilized by LiCl solvation and MgH₂ are accomplished, respectively. In conclusion, dehydrogenation products are B, Mg, LiH, and TiH. Reversibility of nanoconfined 2LiBH₄-MgH₂-0.13TiCl₄ sample is confirmed by the recovery of LiBH₄ after rehydrogenation together with the formation of [B₁₂H₁₂]^{鈭?/sup> derivatives. The superior kinetics during the 2nd, 3rd, and 4th cycles of nanoconfined 2LiBH₄-MgH₂-0.13TiCl₄ to the nanoconfined 2LiBH₄-MgH₂ can be due to the formations of Ti-MgH₂ alloys (Mg_0.25Ti_0.75H₂ and Mg₆TiH₂) during the 1st rehydrogenation.}