The effect of transition metals on hydrogen migration and catalysis in cast Mg-Ni alloys

Cho, Y. H., Aminorroaya, S., Liu, H. K. and Dahle, A. K. (2011) The effect of transition metals on hydrogen migration and catalysis in cast Mg-Ni alloys. International Journal of Hydrogen Energy, 36 8: 4984-4992. doi:10.1016/j.ijhydene.2010.12.090


Author Cho, Y. H.
Aminorroaya, S.
Liu, H. K.
Dahle, A. K.
Title The effect of transition metals on hydrogen migration and catalysis in cast Mg-Ni alloys
Journal name International Journal of Hydrogen Energy   Check publisher's open access policy
ISSN 0360-3199
1879-3487
Publication date 2011-04-01
Sub-type Article (original research)
DOI 10.1016/j.ijhydene.2010.12.090
Open Access Status Not yet assessed
Volume 36
Issue 8
Start page 4984
End page 4992
Total pages 9
Place of publication London, United Kingdom
Publisher Elsevier
Language eng
Subject 2105 Renewable Energy, Sustainability and the Environment
2103 Fuel Technology
3104 Condensed Matter Physics
2102 Energy Engineering and Power Technology
Abstract The inexpensive fabrication technique of casting is applied to develop new Mg-Ni based hydrogen storage alloys with improved hydrogen sorption properties. A nanostructured eutectic Mg-MgNi is formed upon solidification which introduces a large area of interfaces along which hydrogen diffusion can occur with high diffusivity. After a few cycles of hydrogenation and dehydrogenation, an ultrafine porous structure formed in the eutectic Mg-Mg Ni and some cracks developed along the interface between the eutectic and the α-Mg matrix. This indicates that hydrogen atoms introduced into the alloys preferentially migrate along the interfaces in the nanostructured eutectic which enables effective short-range diffusion of hydrogen. Furthermore, transition metals (TMs) such as Nb, Ti and V in the range 240-560 ppm are added directly to molten Mg-10 wt% Ni alloys and are found to form intermetallic compounds with Ni during solidification. The alloys can store 5.6-6.3 wt% hydrogen at 350 °C and 2 MPa. TM-rich intermetallics distributed homogeneously in the cast alloys appear to play a key role in accelerating the nucleation of Mg from MgH upon dehydrogenation. This leads to a significant improvement in the hydrogen desorption kinetics.
Formatted abstract
The inexpensive fabrication technique of casting is applied to develop new Mg-Ni based hydrogen storage alloys with improved hydrogen sorption properties. A nanostructured eutectic Mg-Mg2Ni is formed upon solidification which introduces a large area of interfaces along which hydrogen diffusion can occur with high diffusivity. After a few cycles of hydrogenation and dehydrogenation, an ultrafine porous structure formed in the eutectic Mg-Mg2Ni and some cracks developed along the interface between the eutectic and the α-Mg matrix. This indicates that hydrogen atoms introduced into the alloys preferentially migrate along the interfaces in the nanostructured eutectic which enables effective short-range diffusion of hydrogen. Furthermore, transition metals (TMs) such as Nb, Ti and V in the range 240-560 ppm are added directly to molten Mg-10 wt% Ni alloys and are found to form intermetallic compounds with Ni during solidification. The alloys can store 5.6-6.3 wt% hydrogen at 350 °C and 2 MPa. TM-rich intermetallics distributed homogeneously in the cast alloys appear to play a key role in accelerating the nucleation of Mg from MgH2 upon dehydrogenation. This leads to a significant improvement in the hydrogen desorption kinetics.
Keyword Hydrogen storage
Eutectic Mg-Mg2Ni
Porous structure
Transition metal rich intermetallics
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mechanical & Mining Engineering Publications
 
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