The Effects of Additives on the Dehydrogenation of Amorphous Manganese Borohydride and Its Crystalline Form after Solvent Filtration/Extraction

Robert Varin,Marek Polanski,Leszek Stobinski,Deepak Mattar,Amirreza Bidabadi

doi:10.3390/en10111741

Robert Varin, Marek Polanski + Show 3 more

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https://doi.org/10.3390/en10111741

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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.

Highlights

One of the major challenges facing the world in this century is a transition from a fossil fuels-based economy to one based on renewable, environmentally-friendly resources, such as hydrogen [1,2,3,4].During this transformation, the widespread adoption and usage of fuel cells, in which hydrogen gas (H2 ) in contact with oxygen (O2 ) is converted into electrical energy, must be necessary to realize a world hydrogen economy
The Scanning electron micrographs (SEM) micrographs of the morphology of the as-received ultrafine filamentary Ni and graphene additives are shown in Figure 1a,b, respectively
The SEM micrographs for the as-received NaBH4 and MnCl2 primary reactants were reported by Varin et al [11] and are not shown here

Summary

Introduction

One of the major challenges facing the world in this century is a transition from a fossil fuels-based economy to one based on renewable, environmentally-friendly resources, such as hydrogen [1,2,3,4].During this transformation, the widespread adoption and usage of fuel cells, in which hydrogen gas (H2 ) in contact with oxygen (O2 ) is converted into electrical energy, must be necessary to realize a world hydrogen economy. One of the major challenges facing the world in this century is a transition from a fossil fuels-based economy to one based on renewable, environmentally-friendly resources, such as hydrogen [1,2,3,4]. For the automotive sector, solid-state H2 storage in hydrides has serious constraints, the most important of which is the inability to meet the need for “on board”. This and other very serious constraints preclude a full implementation of solid state H2 storage in the automotive sector [5]

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