2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session T8: Onsager Prize, Nicholson Medal, Apker Award, Davisson-Germer Prize
2:30 PM–5:30 PM,
Wednesday, March 18, 2009
Room: 414/415
Sponsoring
Unit:
DCMP
Chair: Warren Pickett, University of California, Davis
Abstract ID: BAPS.2009.MAR.T8.4
Abstract: T8.00004 : Davisson-Germer Prize Talk: Hydrogen storage in nanoporous materials*
4:18 PM–4:54 PM
Preview Abstract
Abstract
Author:
Yves Chabal
(University of Texas at Dallas)
To develop a hydrogen-based energy technology, several classes of
materials are being considered to achieve the DOE targets for
gravimetric and volumetric hydrogen densities for hydrogen
storage, including liquids (e.g. ammonium borohydrides),
clathrate structures, complex metal hydrides, nanostructured
(e.g. carbon) an nanoporous materials. Fundamental studies
are necessary to determine the ultimate hydrogen capacity of each
system. Nanoporous Metal-organic Framework (MOF) materials are
promising candidates for hydrogen storage because the chemical
nature and size of their unit cell can be tailored to weakly
attract and incorporate H$_{2}$ molecules, with good volumetric
and mass density. In this talk, we consider the structure
M$_{2}$(BDC)$_{2}$(TED), where M is a metal atom (Zn, Ni, Cu),
BDC is benzenedicarboxylate and TED triethylenediamine, to
determine the location and interaction of H$_{2}$ molecules
within the MOF. These compounds are isostructural and crystallize
in the tetragonal phase (space group P4/ncc),
they construct 3D porous structures with relatively large pore
size ($\sim $7-8 A\r{ }), pore volume ($\sim $0.63-0.84 cc/g) and
BET surface area ($\sim $1500-1900 m$^{2}$/g). At high pressures
(300-800 psi), the perturbation of the H-H stretching mode can be
measured with IR absorption spectroscopy, showing a 35 cm$^{-1}$
redshift from the unperturbed ortho (4155 cm$^{-1}$ ) and para
(4161 cm$^{-1}$ ) frequencies. Using a newly
developed non empirical van der Waals DFT method
vdW-DFT),\footnote{J.Y. Lee, D.H. Olson, L. Pan, T.J. Emge, J.
Li, Adv. Func. Mater. 17, 1255 (2007)} it can be shown that the
locus of the deepest H$_{2}$ binding positions lies within to
types of narrow channels. The energies of the most stable binding
sites, as well as the number of such binding sites, are
consistent with the values obtained from experimental adsorption
isotherms, and heat of adsorption)
data.\footnote{M. Dion, H. Ryberg, E. Schroder, D. C. Langreth,
B.I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004).} Importantly,
the calculated shift of the H-H stretch is $\sim $-30 cm$^{-1}$
at the strongest binding points of the two channels, suggesting
that the combination of IR and vdW-DFT gives a consistent and
accurate picture of H$_{2}$ binding in MOF structures. These
methods can therefore provide the fundamental information
necessary to guide synthesis for improving H$_{2}$ uptake and
release.
*This work was supported by the grant DOE-DE-FG02-08ER46491, and performed in collaboration with N. Nijem (UTD), and L. Kong, V. Cooper, K. Li, J. Li and D.C. Langreth (Rutgers University)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.T8.4