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Diffusion of molecular hydrogen in carbon aerogel

Author:
Bahn, Emanuel, Czakkel, Orsolya, Nagy, Balázs, László, Krisztina, Villar-Rodil, Silvia, Tascón, Juan M.D., Demmel, Franz, Telling, Mark T.F., Fouquet, Peter
Source:
Carbon 2016 v.98 pp. 572-581
ISSN:
0008-6223
Subject:
activated carbon, hydrogen, temperature
Abstract:
The diffusion of hydrogen molecules adsorbed in a highly porous carbon aerogel has been studied with quasi-elastic neutron scattering. Hydrogen diffusion in this carbon substrate followed an activated jump process with a single activation barrier. The temperature dependence of the diffusion rate agrees well with previous results from activated carbons and other highly porous carbons. The carbon aerogel sample showed a strongly enhanced conversion between the ortho- and para-hydrogen spin states. The ortho-para conversion process, however, was inhibited for a fraction of the hydrogen molecules. This inhibition process is attributed to a rotational confinement of the hydrogen molecules at the nanometre scale.
Agid:
5595340