Journal
JOURNAL OF POWER SOURCES
Volume 322, Issue -, Pages 179-186Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2016.05.031
Keywords
Magnesium hydride; Incorporation; Surface structure; Dehydriding mechanism
Funding
- National Natural Science Foundation of China [21176145]
- SDUST Research Fund [2014TDJH105, 2014RCJJ019]
- Qingdao Postdoctoral Applied Research Project [2015181]
- Shenzhen Supercomputer Center
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Structural change and dehydriding mechanism of MgH2 with atomic Fe incorporation from reactive ball milling are characterized and simulated by first-principles calculation. Two kinds of hydrides beta- and gamma-MgH2 are formed from Mg powders under hydrogen atmosphere by 3.0 h of milling with pretreated anthracite as milling aid. Experimental studies suggest that the atomic Fe can be incorporated onto MgH2 surface by the shearing effect of Fe-based milling balls on Mg/MgH2 particles. The incorporated Fe has a high dispersity on MgH2 surface and can form atomic clusters FeH4/FeH2 by combining with H anions. The dehydriding reaction of the Fe-incorporated MgH2 begins at hydride surface and shows an enhanced performance with apparent activation energy of 110.3 kJ mol(-1). Theoretical studies suggest that the incorporated Fe can act as a bridge that contributes to electron transfer from H anion to Mg cation before H-2 molecule formation. The intrinsic reason of atomic Fe in catalyzing dehydriding reaction of MgH2 lies in its moderate strength of electron attraction. (C) 2016 Elsevier B.V. All rights reserved.
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