Catalytic effect of transition metals on hydrogen sorption in nanocrystalline ball milled MgH2–Tm (Tm=Ti, V, Mn, Fe and Ni) systems

Liang, Guoxian; Huot, Jacques; Boily, S.; Neste, A. Van; Schulz, Robert

doi:10.1016/s0925-8388(99)00442-9

Cited by 1,029 publications

(644 citation statements)

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“…Our results are consistent with those found by Vajeeston and co-workers. 28 Furthermore, ReaxFF MgH calculates a heat of formation of -20.00 kcal/mol for the R-MgH 2 phase, which is in good 6,9,30 To determine whether a further reduction of grain size below the 20 nm regime could sufficiently destabilize the MgH 2 nanoparticles, we have investigated the enthalpy of formation of ultrasmall MgH 2 particles below the 20 nm regime.…”

Section: Reaction Energiesmentioning

confidence: 99%

ReaxFF_MgH Reactive Force Field for Magnesium Hydride Systems

et al. 2005

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We have developed a reactive force field (ReaxFF MgH ) for magnesium and magnesium hydride systems. The parameters for this force field were derived from fitting to quantum chemical (QM) data on magnesium clusters and on the equations of states for condensed phases of magnesium metal and magnesium hydride crystal. The force field reproduces the QM-derived cell parameters, density, and the equations of state for various pure Mg and MgH 2 crystal phases as well as and bond dissociation, angle bending, charge distribution, and reaction energy data for small magnesium hydride clusters. To demonstrate one application of ReaxFF MgH , we have carried out MD simulations on the hydrogen absorption/desorption process in magnesium hydrides, focusing particularly on the size effect of MgH 2 nanoparticles on H 2 desorption kinetics. Our results show a clear relationship between grain size and heat of formation of MgH 2 ; as the particle size decreases, the heat of formation increases. Between 0.6 and 2.0 nm, the heat of formation ranges from -16 to -19 kcal/Mg and diverges toward that of the bulk value (-20.00 kcal/Mg) as the particle diameter increases beyond 2 nm. Therefore, it is not surprising to find that Mg nanoparticles formed by ball milling (20-100 nm) do not exhibit any significant change in thermochemical properties.

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Section: Reaction Energiesmentioning

confidence: 99%

ReaxFF_MgH Reactive Force Field for Magnesium Hydride Systems

et al. 2005

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“…Magnesium hydride (MgH 2 ) is one of the attractive hydrogen storage materials in the automotive industry since it can be directly formed from the reaction of Mg metal with gaseous hydrogen and has a high hydrogen capacity (7.6 weight %) [1][2][3]. Unfortunately, the application is primarily limited by the high hydrogenation reaction temperature and slow kinetics [4][5].…”

Section: Introductionmentioning

confidence: 99%

Atomic Hydrogen Diffusion in Novel Magnesium Nanostructures: The Impact of Incorporated Subsurface Carbon Atoms

Smith

Yao

et al. 2006

J. Phys.: Conf. Ser.

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“…However, the high thermal stability and slow kinetics of its rutile-type structure significantly hinder its widespread use in commercial energy storage systems. Many factors such as a chemical composition [2][3][4] , addition of catalytic species [5][6][7][8][9][10] , processing technologies 5,[11][12][13][14] and microstructural parameters, particularly grain size 6,[15][16][17] , have an effect on the hydrogen storage capacity, kinetics and/or thermodynamics of Mg-based intermetallic compounds. Conventional crystalline alloys often suffer from relatively slow hydrogen sorption kinetics even at high temperatures, while nanocrystalline and amorphous materials exhibit much faster kinetics at lower temperatures, as their large number of interfaces, defects and grain boundaries, provide easy pathways for hydrogen diffusion [18][19][20][21] .…”

Section: Introductionmentioning

confidence: 99%