Δημοσιεύσεις

Project Acronym: ESECFA
Title: Energy Storage for Eco-Friendly Applications
Affiliation: national technical university of athens
Pi: George K. Papadopoulos
Research Field: engineering

Molecular Dynamics Phenomena of Water in the Metalorganic Framework MIL-100(Al), as Revealed by Pulsed Field Gradient NMR and Atomistic Simulation
by Splith, Tobias, Pantatosaki, Evangelia, Kolokathis, Panagiotis D., Fröhlich, Dominik, Zhang, Kang, Füldner, Gerrit, Chmelik, Christian, Jiang, Jianwen, Henninger, Stefan K., Stallmach, Frank and Papadopoulos, George K.
Abstract:
Measured, via pulsed field gradient (PFG) NMR, and computed molecular dynamics (MD) were utilized for the study of the phase equilibrium and kinetics of water sorbed in a bed of MIL-100(Al) crystallites. The computations rely on our recent methodology for modeling water equilibria and dynamics in the Fe-homologue MIL-100 crystal; in that sense, the particular NMR technique serves also as a validation tool of the previous simulation work which is adapted to the current system. In addition, a computational scheme for assigning partial charges on the host framework atoms was devised; it involves density functional theory (DFT) combined with electronegativity equalization method (EEM) calculations. The derived this way electronegativity, hardness, and gamma parameters for the specific MIL-100(Al) atoms can be used in EEM calculations of other aluminum metalorganic frameworks (MOF) bearing similar atom types. The thermodynamics predictions obtained via MD, comprising equilibria, enthalpies, adsorbate probability densities, and host’s terminal species effects, were compared with data from the real system’s phase equilibria measured in this work. The intracrystalline self-diffusivity of the sorbed water was extracted by means of the spin echo curves obtained by PFG NMR for various guest loadings as a function of observation time and a theoretical short-time expansion of the diffusion coefficient of random walkers, assuming spherical particles under reflecting boundary conditions following Mitra et al. The experimental activation energies for diffusion confirmed previous, in MIL-100(Fe), and current modeling results, with respect to the adsorbed water dynamics and singlet probability density distribution.
Reference:
Molecular Dynamics Phenomena of Water in the Metalorganic Framework MIL-100(Al), as Revealed by Pulsed Field Gradient NMR and Atomistic Simulation (Splith, Tobias, Pantatosaki, Evangelia, Kolokathis, Panagiotis D., Fröhlich, Dominik, Zhang, Kang, Füldner, Gerrit, Chmelik, Christian, Jiang, Jianwen, Henninger, Stefan K., Stallmach, Frank and Papadopoulos, George K.), In The Journal of Physical Chemistry C, volume 121, 2017.
Bibtex Entry:
@article{doi:10.1021-acs.jpcc.7b06240,
 author = {Splith, Tobias and Pantatosaki, Evangelia and Kolokathis, Panagiotis D. and Fröhlich, Dominik and Zhang, Kang and Füldner, Gerrit and Chmelik, Christian and Jiang, Jianwen and Henninger, Stefan K. and Stallmach, Frank and Papadopoulos, George K.},
 title = {Molecular Dynamics Phenomena of Water in the Metalorganic Framework MIL-100(Al), as Revealed by Pulsed Field Gradient NMR and Atomistic Simulation},
 journal = {The Journal of Physical Chemistry C},
 volume = {121},
 number = {33},
 pages = {18065-18074},
 year = {2017},
 bibyear = {2017},
 doi = {10.1021/acs.jpcc.7b06240},
 url = {http://dx.doi.org/10.1021/acs.jpcc.7b06240},
 eprint = {http://dx.doi.org/10.1021/acs.jpcc.7b06240},
 abstract = { Measured, via pulsed field gradient (PFG) NMR, and computed molecular dynamics (MD) were utilized for the study of the phase equilibrium and kinetics of water sorbed in a bed of MIL-100(Al) crystallites. The computations rely on our recent methodology for modeling water equilibria and dynamics in the Fe-homologue MIL-100 crystal; in that sense, the particular NMR technique serves also as a validation tool of the previous simulation work which is adapted to the current system. In addition, a computational scheme for assigning partial charges on the host framework atoms was devised; it involves density functional theory (DFT) combined with electronegativity equalization method (EEM) calculations. The derived this way electronegativity, hardness, and gamma parameters for the specific MIL-100(Al) atoms can be used in EEM calculations of other aluminum metalorganic frameworks (MOF) bearing similar atom types. The thermodynamics predictions obtained via MD, comprising equilibria, enthalpies, adsorbate probability densities, and host’s terminal species effects, were compared with data from the real system’s phase equilibria measured in this work. The intracrystalline self-diffusivity of the sorbed water was extracted by means of the spin echo curves obtained by PFG NMR for various guest loadings as a function of observation time and a theoretical short-time expansion of the diffusion coefficient of random walkers, assuming spherical particles under reflecting boundary conditions following Mitra et al. The experimental activation energies for diffusion confirmed previous, in MIL-100(Fe), and current modeling results, with respect to the adsorbed water dynamics and singlet probability density distribution. },
}