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ID 32009
file
creator
Yamane, Aki
Shimojo, Fuyuki
NDC
Physics
abstract
The hydrogen storage system LiH + NH_3 <-> LiNH_2 + H_2 is one of the most promising hydrogen storage systems, where the reaction yield can be increased by replacing Li in LiH with other alkali metals (Na or K) in order of Li < Na < K. In this paper, we have studied the alkali metal M (M = Li, Na, K) dependence of the reactivity of MH with NH_3 by calculating the potential barrier of the H_2 desorption process from the reaction of an M_2H_2 cluster with an NH_3 molecule based on the ab initio structure optimization method. We have shown that the height of the potential barrier becomes lower in order of Li, Na, and K, where the difference of the potential barrier in Li and Na is relatively smaller than that in Na and K, and this tendency is consistent with the recent experimental results. We have also shown that the H-H distance of the H_2 dimer at the transition state takes larger distance and the change of the potential energy around the transition state becomes softer in order of Li, Na, and K. There are almost no M dependence in the charge of the H atom in NH_3 before the reaction, while that of the H atom in M_2H_2 takes larger negative value in order of Li, Na, and K. We have also performed molecular dynamics simulations on the M_2H_2-NH_3 system and succeeded to reproduce the H_2 desorption from the reaction of Na_2H_2 with NH_3.
journal title
Journal of Chemical Physics
volume
Volume 134
issue
Issue 12
start page
124515-1
end page
124515-8
date of issued
2011-03-29
publisher
American Institute of Physics
issn
0021-9606
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2011 American Institute of Physics.
relation url
department
Graduate School of Integrated Arts and Sciences
Graduate School of Advanced Sciences of Matter
Institute for Advanced Materials Research