Li-decorated metal–organic framework 5: A route to achieving a suitable hydrogen storage medium

*Condensed Matter Theory Group, Department of Physics, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden;
^†Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand; and
^‡Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Edited by Ho-kwang Mao, Carnegie Institution of Washington, Washington, DC, and approved October 29, 2007 (received for review September 11, 2007)

Abstract

A significant improvement in molecular hydrogen uptake properties is revealed by our ab initio calculations for Li-decorated metal–organic framework 5. We have found that two Li atoms are strongly adsorbed on the surfaces of the six-carbon rings, one on each side, carrying a charge of +0.9e per Li atom. Each Li can cluster three H₂ molecules around itself with a binding energy of 12 kJ (mol H₂)⁻¹. Furthermore, we show from ab initio molecular dynamics simulations with a hydrogen loading of 18 H₂ per formula unit that a hydrogen uptake of 2.9 wt % at 200 K and 2.0 wt % at 300 K is achievable. To our knowledge, this is the highest hydrogen storage capacity reported for metal–organic framework 5 under such thermodynamic conditions.

Footnotes

^§To whom correspondence should be addressed. E-mail: rajeev.ahuja{at}fysik.uu.se
Author contributions: A.B., C.M.A., and R.A. designed research; A.B. and C.M.A. performed research; A.B., C.M.A., P.S., and R.A. analyzed data; and A.B., C.M.A., and R.A. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.