Journal
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
Volume 42, Issue 2, Pages 1012-1017Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijhydene.2016.08.152
Keywords
Rare-earth elements; MgH2; specific capacity; Density of states; De-hydrogenation efficiency
Categories
Ask authors/readers for more resources
Effect on de-hydrogenation efficiency on doping of rare earth elements Pr, Nd, Gd and Dy in MgH2 was studied using density functional theory. Specific storage capacity both in terms of volumetric and gravimetric capacity was also studied. Volumetric capacity was shown to decrease with the trends Dy > Gd > Nd > Pr, in accordance with the increase of unit cell volume, while gravimetric capacity was shown to decrease with the same trend in accordance with their atomic mass number. Analysis of density of states exhibits the presence of H-s states across Fermi energy, only for nearest neighbor H-atoms of rare earth (RE) dopants. These states are formed due to the delocalization of H-s states arising from the shorter Mg-H bond length, while Mg remain connected with a nearest neighbor H of RE dopant and due to the superposition and hence polarization of H-s states with f-orbital of RE elements across Fermi energy. Accordingly, H-2 desorption can be predicted to occur only from the nearest neighbor H atoms of RE dopant. Pr and Nd were shown to affect the dehydrogenation efficiency similarly as La and Ce doping in MgH2 as obtained in our previous work. It is seen that Pr and Nd doping will reduce the H-2 desorption temperature as La and Ce in MgH2, while, Gd and Dy doping will act negatively by increasing the desorption temperature even in comparison to pure MgH2. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available