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Intra-cage dynamics of molecular hydrogen confined in cages of two different dimensions of clathrate hydrates

Russina, Margarita; Kemner, Ewout and Mezei, Ferenc LU (2016) In Scientific Reports 6.
Abstract

In porous materials the molecular confinement is often realized by means of weak Van der Waals interactions between the molecule and the pore surface. The understanding of the mechanism of such interactions is important for a number of applications. In order to establish the role of the confinement size we have studied the microscopic dynamics of molecular hydrogen stored in the nanocages of clathrate hydrates of two different dimensions. We have found that by varying the size of the pore the diffusive mobility of confined hydrogen can be modified in both directions, i.e. reduced or enhanced compared to that in the bulk solid at the same temperatures. In the small cages with a mean crystallographic radius of 3.95 Å the confinement... (More)

In porous materials the molecular confinement is often realized by means of weak Van der Waals interactions between the molecule and the pore surface. The understanding of the mechanism of such interactions is important for a number of applications. In order to establish the role of the confinement size we have studied the microscopic dynamics of molecular hydrogen stored in the nanocages of clathrate hydrates of two different dimensions. We have found that by varying the size of the pore the diffusive mobility of confined hydrogen can be modified in both directions, i.e. reduced or enhanced compared to that in the bulk solid at the same temperatures. In the small cages with a mean crystallographic radius of 3.95 Å the confinement reduces diffusive mobility by orders of magnitude. In contrast, in large cages with a mean radius of 4.75 Å hydrogen molecules displays diffusive jump motion between different equilibrium sites inside the cages, visible at temperatures where bulk H 2 is solid. The localization of H 2 molecules observed in small cages can promote improved functional properties valuable for hydrogen storage applications.

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organization
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type
Contribution to journal
publication status
published
subject
in
Scientific Reports
volume
6
publisher
Nature Publishing Group
external identifiers
  • scopus:84976349066
ISSN
2045-2322
DOI
10.1038/srep27417
language
English
LU publication?
yes
id
fbe799ad-35be-41ab-9513-8d61da1ccbb0
date added to LUP
2017-01-24 11:50:31
date last changed
2017-09-27 13:42:02
@article{fbe799ad-35be-41ab-9513-8d61da1ccbb0,
  abstract     = {<p>In porous materials the molecular confinement is often realized by means of weak Van der Waals interactions between the molecule and the pore surface. The understanding of the mechanism of such interactions is important for a number of applications. In order to establish the role of the confinement size we have studied the microscopic dynamics of molecular hydrogen stored in the nanocages of clathrate hydrates of two different dimensions. We have found that by varying the size of the pore the diffusive mobility of confined hydrogen can be modified in both directions, i.e. reduced or enhanced compared to that in the bulk solid at the same temperatures. In the small cages with a mean crystallographic radius of 3.95 Å the confinement reduces diffusive mobility by orders of magnitude. In contrast, in large cages with a mean radius of 4.75 Å hydrogen molecules displays diffusive jump motion between different equilibrium sites inside the cages, visible at temperatures where bulk H 2 is solid. The localization of H 2 molecules observed in small cages can promote improved functional properties valuable for hydrogen storage applications.</p>},
  articleno    = {27417},
  author       = {Russina, Margarita and Kemner, Ewout and Mezei, Ferenc},
  issn         = {2045-2322},
  language     = {eng},
  month        = {06},
  publisher    = {Nature Publishing Group},
  series       = {Scientific Reports},
  title        = {Intra-cage dynamics of molecular hydrogen confined in cages of two different dimensions of clathrate hydrates},
  url          = {http://dx.doi.org/10.1038/srep27417},
  volume       = {6},
  year         = {2016},
}