| 1. |
- Korablov, Dmytro, et al.
(författare)
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Activation effects during hydrogen release and uptake of MgH2
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:18, s. 9888-9892
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Tidskriftsartikel (refereegranskat)abstract
- Scandium(II)hydride, ScH2, and scandium(III)chloride, ScCl3, are explored as additives to facilitate hydrogen release and uptake for magnesium hydride. These additives are expected to form more homogeneous composites with Mg/MgH2 as compared to metallic scandium. However, scandium(III)chloride, reacts with MgH2 during mechano-chemical treatment and form ScH2 and MgCl2 (that later crystallise during heat treatment). The composite MgH2-ScH2 was investigated using in-situ synchrotron radiation powder X-ray diffraction during up to five cycles of continuous release and uptake of hydrogen at isothermal conditions at 320, 400 and 450 degrees C and p(H-2) = 100-150 or 10(-2) bar. The data were analysed by Rietveld refinement and no reaction is observed between either MgH2/ScH2 or Mg/ScH2 during cycling. The extracted sigmoidal shaped curves for formation or decomposition of Mg/MgH2 suggest that a nucleation process is preceding the crystal growth. The reaction rate increases with increasing number of cycles of hydrogen release and uptake at isothermal conditions possibly due to activation effects. This kinetic enhancement is strongest between the first cycles and may be denoted an activation effect. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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| 2. |
- Merte, Lindsay, et al.
(författare)
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Water clustering on nanostructured iron oxide films
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire structure.
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