The Effects of Additives on the Dehydrogenation of Amorphous Manganese Borohydride and Its Crystalline Form after Solvent Filtration/Extraction
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Date
2017-10-30
Authors
Varin, Robert A.
Mattar, Deepak
Polanski, Marek
Bidabadi, Amirreza
Stobinski, Leszek
Journal Title
Journal ISSN
Volume Title
Publisher
Multidisciplinary Digital Publishing Institute
Abstract
A non-stoichiometric, amorphous a-Mn(BH4)(2x) hydride, accompanied by a NaCl-type salt, was mechanochemically synthesized from the additive-free mixture of (2NaBH4 + MnCl2), as well as from the mixtures containing the additives of ultrafine filamentary carbonyl nickel (Ni), graphene, and LiNH2. It is shown that both graphene and LiNH2 suppressed the release of B2H6 during thermal gas desorption, with the LiNH2 additive being the most effective suppressor of B2H6. During solvent filtration and extraction of additive-free, as well as additive-bearing, (Ni and graphene) samples from diethyl ether (Et2O), the amorphous a-Mn(BH4)(2x) hydride transformed into a crystalline c-Mn(BH4)2 hydride, exhibiting a microstructure containing nanosized crystallites (grains). In contrast, the LiNH2 additive most likely suppressed the formation of a crystalline c-Mn(BH4)2 hydride during solvent filtration/extraction. In a differential scanning calorimeter (DSC), the thermal decomposition peaks of both amorphous a-Mn(BH4)(2x) and crystalline c-Mn(BH4)2 were endothermic for the additive-free samples, as well as the samples with added graphene and Ni. The samples with LiNH2 exhibited an exothermic DSC decomposition peak.
Description
Keywords
ball milling, diborane suppression, gas desorption behavior, graphene, solvent filtration/extraction, mechanochemical activation synthesis of NaBH4 and MnCl2, amorphous a-Mn(BH4)2-type, filamentary Ni and LiNH2 additives on desorption, crystalline c-Mn(BH4)2