Catalytic effects of metal oxide on hydrogen absorption of magnesium metal hydride

Jung, Keum‐Dong; Lee, E.Y.; Lee, K.S.

doi:10.1016/j.jallcom.2005.09.085

Cited by 88 publications

(33 citation statements)

References 20 publications

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“…• C and the cycling stability over the 60 cycles that the sample was subjected to, are comparable to some of the high-performance, transition metal-and transition metal oxide-catalysed, 147.7 ± 6.0 [13][14][15][16]. The structural characterisation of the thin film samples shows that, in all three cases coatings in the range of 2.5 µm -2.74 µm were fabricated.…”

Section: Discussionmentioning

confidence: 63%

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Fry

Grant

Walker

2014

International Journal of Hydrogen Energy

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This paper explores the hydrogen cycling properties of Mg/Cr and Mg/V multilayer thin films and studies the effect of chromium and vanadium transition metal catalysts on the cycling properties of thick magnesium coatings. Two transition-metal catalysed magnesium-based multilayer PVD coatings are compared with a non-catalysed magnesium control sample. The (micro-)structural evolution of the thin film coatings into fine, flakey powders is studied in-depth using XRD, SEM and TEM and the hydrogen storage properties of all three materials are assessed using volumetric, gravimetric and calorimetric methods focussing on the effect of the microstructure and composition of the coatings on the hydrogen storage kinetics. It was found that the chromiumcatalysed coating had the most favourable hydrogen storage kinetics with an activation energy for the dehydrogenation reaction of 65.7 ± 2.5 kJ mol −1 and a hydrogen capacity of 6.1 ± 0.3 wt%. The mechanism of the dehydrogenation reaction of the catalysed samples was studied using the CV and JMAK kinetic models and it was found that the catalyst material influenced not only the hydrogen storage kinetics but also the mechanism of the reaction.

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Section: Discussionmentioning

confidence: 63%

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Fry

Grant

Walker

2014

International Journal of Hydrogen Energy

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“…Vanadium(V) oxide, similar to niobium (V) oxide, is readily reduced in contact with hydrogen or mechano-chemically treated with MgH 2 (Jung et al, 2006;Nielsen and Jensen, 2012). Several lower oxides may act as intermediates during the formation of MgO.…”

Section: E On the Catalytic Properties Of Vanadium Pentoxide And Vanmentioning

confidence: 99%

“…Transition metal oxides are also good catalysts for enhancement of hydrogen release and uptake e.g., Nb 2 O 5 (Barkhordarian et al, 2006) and V 2 O 5 (Oelerich et al, 2001a(Oelerich et al, , 2001bJung et al, 2006). A drawback may be that some metal oxides have a tendency to reduce during cycling hydrogen release and uptake, which leads to the formation of inert magnesium oxide.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and kinetics of early transition metal hydrides, oxides, and chlorides to enhance hydrogen release and uptake properties of MgH₂

2015

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Selected hydrides (TiH 2 , ZrH 2 ), chlorides (VCl 3 , ScCl 3 ) or oxides (V 2 O 5 ) utilized as additives facilitating hydrogen release and uptake for magnesium hydride were investigated using mechanochemical treatment and in-situ synchrotron radiation powder X-ray diffraction studies. The fastest hydrogen desorption and absorption kinetics for MgH 2 was observed for a sample with 5 mol% V 2 O 5 at 320°C. Additional activation of the system (2 cycles, vacuum/p(H 2 ) ∼150 bar, 450°C) leads to significant improvement of the kinetics even at lower temperatures, 270°C. The observed prolific effect is achieved through the full reduction of vanadium oxides and formation of an efficient vanadium catalyst as nanoparticles and possibly interfacial effects in the MgO/Mg/MgH 2 /V system introduced during cycling hydrogen release and uptake in hydrogen/dynamic vacuum at 450°C. Nanostructuring as well as hydrogen permeability via vanadium nanoparticles may improve kinetics and reduce the apparent activation energy for hydrogen release. Thus, the enhancement of hydrogen release/uptake in the MgH 2 owe to "in situ" formation of vanadium nanoparticles by reduction of V 2 O 5 .

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“…Even if presently the performances in terms of sorption rate are still far from the targets for technological applications (DOE, Department of Energy, Washington DC, USA) [5], the reactions of Mg with H 2 have been significantly accelerated by nanostructuring the material generally performed by ball milling with catalyst addition. In fact, the introduction of defects, the refinement of particle size and the presence of catalyst particles play an important role in reducing the working temperature and in speeding up the reaction rate with H 2 [6,7].…”

Section: Introductionmentioning

confidence: 99%

Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling

et al. 2012

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The effect of extended H 2 sorption cycles on the structure and on the hydrogen storage performances of MgH 2 powders with 5 wt% of Fe particle catalyst is reported. MgH 2 powders with and without Fe have been ball milled under Argon, the doped MgH 2 nanocomposite has been cycled under hydrogen pressure up to a maximum of 47 desorption and absorption cycles at 300 °C. After acceleration during the first 10 cycles, the kinetics behavior of doped MgH 2 is constant after extended cycling, in terms of maximum storage capacity and rate of sorption. The major effect of cycling on particle morphology is the progressive extraction of Mg from the MgO shell surrounding the powder particles. The Mg extraction from the MgO shell leaves the catalyst particles inside the hydride particles. Many empty MgO shells are observed in the pure ball milled MgH 2 upon cycling at higher temperature, suggesting that this enhancement of the extraction efficiency is related to the higher operating temperature which favors Mg diffusivity with respect to the H ion one.

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Catalytic effects of metal oxide on hydrogen absorption of magnesium metal hydride

Cited by 88 publications

References 20 publications

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Mechanism and kinetics of early transition metal hydrides, oxides, and chlorides to enhance hydrogen release and uptake properties of MgH₂

Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling

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Catalytic effects of metal oxide on hydrogen absorption of magnesium metal hydride

Cited by 88 publications

References 20 publications

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Catalysis and evolution on cycling of nano-structured magnesium multilayer thin films

Mechanism and kinetics of early transition metal hydrides, oxides, and chlorides to enhance hydrogen release and uptake properties of MgH2

Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling

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Mechanism and kinetics of early transition metal hydrides, oxides, and chlorides to enhance hydrogen release and uptake properties of MgH₂