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Probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi-elastic neutron scattering experiments

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Title Probing the hydrogen equilibrium and kinetics in zeolite imidazolate
frameworks via molecular dynamics and quasi-elastic neutron scattering
experiments
 
Creator Pantatosaki, Evangelia
Jobic, Hervé
Kolokolov, Daniil I
Karmakar, Shilpi
Biniwale, Rajesh
 
Subject Materials Science
 
Description The problem of simulating processes involving equilibria and dynamics of guest sorbates within
zeolitic imidazolate frameworks (ZIF) by means of molecular dynamics (MD) computer experiments
is of growing importance because of the promising role of ZIFs as molecular “traps” for clean energy
applications. A key issue for validating such an atomistic modeling attempt is the possibility of
comparing the MD results, with real experiments being able to capture analogous space and time
scales to the ones pertained to the computer experiments. In the present study, this prerequisite is
fulfilled through the quasi-elastic neutron scattering technique (QENS) for measuring self-diffusivity,
by elaborating the incoherent scattering signal of hydrogen nuclei. QENS and MD experiments were
performed in parallel to probe the hydrogen motion, for the first time in ZIF members. The predicted
and measured dynamics behaviors show considerable concentration variation of the hydrogen selfdiffusion
coefficient in the two topologically different ZIF pore networks of this study, the ZIF-3
and ZIF-8. Modeling options such as the flexibility of the entire matrix versus a rigid framework
version, the mobility of the imidazolate ligand, and the inclusion of quantum mechanical effects
in the potential functions were examined in detail for the sorption thermodynamics and kinetics
of hydrogen and also of deuterium, by employing MD combined with Widom averaging towards
studying phase equilibria. The latter methodology ensures a rigorous and efficient way for postprocessing
the dynamics trajectory, thereby avoiding stochastic moves via Monte Carlo simulation,
over the large number of configurational degrees of freedom a nonrigid framework encompasses.
© 2013 American Institute of Physics.
 
Publisher AIP
 
Date 2013
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://neeri.csircentral.net/1102/1/Journal%20of%20chem%20phy%202013.pdf
Pantatosaki, Evangelia and Jobic, Hervé and Kolokolov, Daniil I and Karmakar, Shilpi and Biniwale, Rajesh (2013) Probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi-elastic neutron scattering experiments. The Journal of Chemical Physics, 138 (3). ISSN 0021-9606
 
Relation http://aip.scitation.org/journal/jcp
http://neeri.csircentral.net/1102/