Stability, Electronic Structure and Thermodynamic Properties of Nanostructured MgH2 Thin Films

Abstract

Magnesium is an attractive hydrogen storage candidate due to its high gravimetric and volumetric storage capacities (7.6 wt.% and 110 gH2/l, respectively). Unfortunately, its use as a storage material for hydrogen is hampered by the high stability of its hydride, its high dissociation temperature of 573–673 K and its slow reaction kinetics. In order to overcome those drawbacks, an important advancement toward controlling the enthalpy and desorption temperatures of nano-structured MgH2 thin films via stress/strain and size effects is presented in this paper, as the effect of the nano-structuring of the bulk added to a biaxial strain on the hydrogen storage properties has not been previously investigated. Our results show that the formation heat and decomposition temperature correlate with the thin film’s thickness and strain/stress effects. The instability created by decreasing the thickness of MgH2 thin films combined with the stress/strain effects induce a significant enhancement in the hydrogen storage properties of MgH2.

Structures and Electronic and Hydrogen Storage Properties of Magnesium Scandium Hydrides

“…It is well known that metal hydrides are very effective and mature hydrogen storage materials, which have been studied in a large number of experimental and theoretical studies. − For example, the tetragonal α-MgH 2 with the P 4 2 / mnm space group, which has high gravimetric density and volumetric capacity (7.6 wt % and 110 g/L), has been proved to be a promising hydrogen storage material. Unfortunately, its high thermodynamic stability (Δ H = −75 kJ·mol –1 H 2 ), high dissociation temperature (573–673 K), slow absorption and desorption kinetics severely limit its application in industries. These characteristics are unfavorable for the hydrogenation reaction at room temperature.…”

Methane and Carbon Dioxide Hydrate Formation in the Presence of Metal-Based Fluid

“…The term “nanofluid” describes a collision of nanoparticles, mostly below 100 nm, dispersed in a liquid phase. Several dispersion techniques are used to prepare the nanofluids, such as surface modification of nanoparticles, adding surfactants to the base liquid, and ultrasonication [ 13 ]. In 2006, copper nanoparticles were utilized by Li et al, as a hydrate promoter for 1,1,1,2-Tetrafluoroethane (HFC134a) [ 14 ].…”