Synthesis of magnesium and titanium hydride via reactive mechanical alloying

Bobet, Jean-Louis; Even, Christophe; Nakamura, Yumiko; Akiba, Etsuo; Darriet, B.

doi:10.1016/s0925-8388(99)00628-3

Cited by 133 publications

(114 citation statements)

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“…E F (eV) Bulk Rutile MgH 2 1.64 (MgH 2 ) 2 2.01 (MgH 2 ) 3 0.60 (MgH 2 ) 4 0.22 (MgH 2 ) 5 0.01 (MgH 2 ) 6 0.00 (MgH 2 ) 7 0.21 (MgH 2 ) 8 -0.08 (MgH 2 ) 9 0.00 (MgH 2 ) 10 0.15 As Ni dopants have a significant effect on the geometry and electronic structure of the MgH 2 cluster, we also calculated the effects on the dehydrogenation thermodynamics. In particular we calculate the removal energy for first H 2 removal from both the undoped and Ni-doped MgH 2 clusters, see We calculated the charge deformation density in order to understand the effects of Ni dopants on the electronic structure of the MgH 2 clusters and thus the mechanism behind the reduced removal energy, see Figure 5.…”

Section: 2: Nickel Dopingmentioning

confidence: 99%

“…2,3,4,5,6,7 A favoured material for hydrogen storage is magnesium hydride (MgH 2 ), as it has a high gravimetric hydrogen storage capacity of 7.6 wt% and is cheap and plentiful. However, unmodified MgH 2 is not suitable for technological applications due to a high enthalpy for dehydrogenation of 77 kJ/mol, 8 low plateau pressure of 10 Pa at ambient temperature and pressure, 9 and relatively slow absorption and desorption kinetics. 10 Nanostructuring and doping are popular methods of modifying properties of materials, as is the case for MgH 2 .…”

Section: : Introductionmentioning

confidence: 99%

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MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

Shevlin

Guo

2013

J. Phys. Chem. C

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Controversy currently exists as to the true effects of nanostructuring and transition-metal doping on the dehydrogenation of MgH 2 . Following extensive datamining of structurally related compounds, we present for the first time, especially for the larger clusters, new stable structures for (MgH 2 ) n clusters, where n = 1 to 10. Using density functional theory and the harmonic approximation we determine the enthalpy of dehydrogenation for all of these clusters. All clusters have very different structures from the bulk, with one-to fourfold hydrogen coordinations observed, and three-to seven-fold magnesium coordinations. We find that, apart from the smallest clusters, enthalpy is larger than for the bulk. Nanostructuring does not improve dehydrogenation enthalpies. We attribute this to surface energy effects; as the (MgH 2 ) n clusters reduce in size bulk cuts become less stable until a stabilising reconstruction occurs which strongly modifies the cluster structure. This increases the magnitude of the dehydrogenation enthalpy. Accurately determining the structures of clusters is essential in determining gas-release thermodynamics for applications. Additionally we investigate modifications of these

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Section: 2: Nickel Dopingmentioning

confidence: 99%

Section: : Introductionmentioning

confidence: 99%

MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

Shevlin

Guo

2013

J. Phys. Chem. C

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“…It has also been shown that mechanical grinding in a reactive atmosphere promotes the solid-gas reaction. Such a procedure has been used to produce nitrides, oxides and hydrides [8] at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of reactive mechanical grinding on chemical and hydrogen sorption properties of the Mg+10 wt.% Co mixture

Bobet

Chevalier

Darriet

2002

Journal of Alloys and Compounds

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:Reactive mechanical grinding (MG under H 2 ) of magnesium powder improves the hydrogen sorption properties. The hydrogenation of Mg starts in situ during the milling process that allows suppressing the activation procedure generally requested for Mg. The addition of Co, which acts as a catalyst for the dissociation of H 2 , also leads to an improvement of the hydrogen sorption properties (but a strong dependence upon the milling time is reported). The hydriding is determined to be a two-step process: nucleation and diffusion. A direct relationship exists between the nucleation duration and the specific surface. A critical milling time exists below which the diffusion process is improved and above which no more improvement is observed (the maximum internal stress in the powder is also reached at this critical time). The diffusion is controlled by the number of crystallites per particle which can be decreased by increasing the milling time up to 10 h. However, the sorption properties of Mg-Co mixtures are a little under those reported for MgH 2 -metal mixtures.

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“…For example, Bobet et al [82,[122][123][124] synthesized MgH 2 via RMA at room temperature and studied the influence of addition of 3d-metals on the synthesis. It was observed that addition of 10 wt.% Co as a catalyst increased the yield of MgH 2 to 71% after 10 h of milling.…”

Section: Magnesium Hydride and Its Nanostructuresmentioning

confidence: 99%

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

2008

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Hydrogen is gaining a great deal of attention as an energy carrier as well as an alternative fuel. However, in order to fully implement the so called 'hydrogen economy' significant technical challenges need to be overcome in the fields of production and storage of hydrogen and its point of use especially in fuel cells for the automotive industry. The purpose of this review is to present and discuss recent advances in the use of nanomaterials for solar hydrogen production and on-board solid state storage of hydrogen. The role of nanotechnology in enhancing the efficiency of fuel cells and reducing their cost is also discussed.

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Synthesis of magnesium and titanium hydride via reactive mechanical alloying

Cited by 133 publications

References 11 publications

MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

Effect of reactive mechanical grinding on chemical and hydrogen sorption properties of the Mg+10 wt.% Co mixture

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

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Synthesis of magnesium and titanium hydride via reactive mechanical alloying

Cited by 133 publications

References 11 publications

MgH2 Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

MgH2 Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

Effect of reactive mechanical grinding on chemical and hydrogen sorption properties of the Mg+10 wt.% Co mixture

Advances in the application of nanotechnology in enabling a ‘hydrogen economy’

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Product

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About

MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping

MgH₂ Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping