Effects of nano size mischmetal and its oxide on improving the hydrogen sorption behaviour of MgH2

Hydrogen storage properties of nanocrystalline and amorphous Pr–Mg–Ni-based alloys synthesized by mechanical milling

“…Moreover, mechanical milling can reduce the grain size and increase the internal strain energy, which are also helpful to improve gaseous kinetics, especially the hydrogen desorption kinetics. It is reported that reducing grain size to nanometer level can dramatically speed up the hydriding/dehydriding rate of alloys [14]. In addition, Northwood et al [27] considered that the stored internal strain will grow with increasing milling time, which consequentially causes a significant decline in the stability of metal hydrides, and facilitates the development of hydrogen desorption process.…”

“…The total energy is defined as activation energy, which is a critical determinant of the kinetics of a gasesolid reaction. For facilitating the dehydrogenation reaction, it has to provide enough energy to overcome the total energy barrier [14]. Hence, the activation energy is considered as the determine factor of dehydrogenation reaction, which can be calculated by using Arrhenius and Kissinger methods.…”

“…It has been reported that the gaseous kinetics performances are very sensitive to their structures [12]. Particularly, reducing the grain sizes to nanometer level can dramatically speed up hydriding/dehydriding rate of the alloys [13,14]. Some techniques, including: (a) rapid solidification (RS) [15], (b) mechanical milling (MA) [16], (c) equal channel angular pressing (ECAP) [17], (d) hydriding combustion synthesis [18] have been used to prepare nanocrystalline and amorphous alloys.…”

An investigation on hydrogen storage thermodynamics and kinetics of Nd–Mg–Ni-based alloys synthesized by mechanical milling

“…Generally, the gasesolid reaction activation energy represents the total potential barrier that a gasesolid reaction must overcome, which is considered to be a determining factor of the gasesolid reaction kinetics. As far as gaseous hydrogen desorption reaction is concerned, it is usually believed to be associated with total energy barrier concerning hydrogen desorption processes [34]. Hence, we can determine the driving force of hydrogen desorption reaction according to the change of activation energy.…”

In-situ catalyzation approach for enhancing the hydrogenation/dehydrogenation kinetics of MgH2 powders with Ni particles

“…In general, it is agreed that mechanically-induced doping of MgH 2 with the abrasive powders of hard phases such as carbides, oxides, intermetallic and metallic glassy alloys materials lead to fast grain refining of the MgH 2 upon releasing the crystalline stored energy, leading to refine the MgH 2 grains along their grain boundaries where superfine grains are formed. Such desirable fine grains with their short-distance grain boundaries always facilitate short diffusion path20, leading to fast diffusion of the hydrogen atoms212223. Recently, Crivello et al .…”