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In this paper, attention in focused on the nanostructured magnesium films for hydrogen storage. It is shown that 2 μm thick Mg film is transformed into MgH2 film under high-flux and fluence hydrogen plasma immersion ion implantation at 450 K for 15 mm. All hydrogen desorbs around 530 K temperature, which corresponds to the decomposition of MgH2 -> Mg + H2. The Mg-based hydrides compounds are too stable for practical applications and can be destabilized by adding small amount of transition metals (Ti, V, Ni). The results provide new aspects of hydriding of thin nanocrystalline film materials under highly nonequalibrium conditions on the surface and destabilization oh hydrides using additives. [ABSTRACT FROM AUTHOR]

The thick layered magnesium-nickel structures for hydrogen storage were prepared using magnetron sputtering technology. The received structures were studied using XRD, SEM, EDX. It was found that Mg and Ni layers do not mix in any of structures (Mg/Ni/Mg, ∼60 μm thickness and Mg/Ni/Mg/Ni/Mg, -100 μm thickness). The hydrogen sorption-desorption cycling of layered Mg/Ni structures were investigated. [ABSTRACT FROM AUTHOR]

Depleting fossil resources and environmental concerns are raising great interest in renewable energy. Unfortunately, renewable energy sources are not equally available throughout time and require energy storage systems to balance supply and demand. Hydrogen as a way of chemical energy storage has a great potential to solve a whole set of energy related problems. A lot of efforts have been made to find a perfect solid state hydrogen storage material which would have high hydrogen storage capacity, proper thermodynamic properties and good cycling stability [1-3]. However, no single material was able to meet the requirement and it became clear that different sorts of material engineering is needed. Traditionally scientist looked for solutions which would improve the bulk properties of the hydride. The biggest step at improving hydrogen storage by changing their bulk properties was achieved by Bogdanavic when he added titanium chloride to sodium alanate [4-5]. Later it was realised that surface properties of the hydrogen storage materials can be equally important. It was shown that for particular materials hydrogenation kinetics can have a limiting step of H2 dissociation at the surface or diffusion from the surface to the bulk. Various surface catalyst such as Pd, V and Ni significantly increased the hydrogenation kinetics but as with the bulk improvement their effect was not enough to achieve targets set by international energy agencies and industry. During current research it was tested if manipulation of thin film-substrate interaction zone and controlling free surface energy could have significant effects on hydrogenation properties of thin films deposited by magnetron sputtering. For this purpose we have chosen to use a well known and widely described Mg based materials and to deposit them on to the different substrates affected by different plasma treatment. The received experimental data has revealed interesting material behaviour under hydrogenation and provided experimental proof of concept that different surface pretreatment can be used to alter the overall hydrogenation properties of metal hydrides. [ABSTRACT FROM AUTHOR]

Light-weight hydrides, such as borohydrides, are considered as prospective materials for hydrogen storage. Their stability is determined by electron transfer from metal atoms to the BH4 anion: the lower the electropositivity of the metal atom the lower the decomposition temperature. Consequently, alkali metal borohydrides are mere ionic salts, too stable for practical applications. Recently, combination of two metals in "bimetallic borohydrides" allowed to extend the series to many more elements. Structural chemistry of bimetallic borohydrides is much more versatile □ the less electropositive metal forms a complex anion with BH4 groups, while the more electropositive metal is donating electrons to the complex anion. The decomposition temperatures are mostly determined by the electropositivity of the complex-forming metal [1]. Another step of structural design can be made by using coordination properties of the borohydride anion. Directional and partly covalent metal-BH4 bonding results in complex stochiometries and/or formation of relatively complex framework structures. Most recently, we obtained the first porous hydride capable to store reversibly guest molecules [2]. This MOF-like structure reveals specific guest-host interactions and selective gas adsorption properties. Similar to imidazolate frameworks, the directionality of the BH4 ligand is instrumental to the existence of "metal borohydride frameworks", and thus prompts a combined use of BH4 and other directional ligands in creation of hybrid materials. In-situ X-ray powder diffraction is our most valuable and versatile tool to study chemistry of hydrides [3]. [ABSTRACT FROM AUTHOR]