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V. V. TUROV, V. M. GUN’KO, A. Yu. PETIN, P. P. GORBYK, M. V. BORYSENKO, V. M. BARVINCHENKO, K. N. KHOMENKO, and Yu. O. TARASENKO
«Coabsorption of Hydrogen and Water in Nanostructured Materials by the Data of 1H- NMR Spectroscopy»
PACS numbers: 61.46.Bc, 81.16.Dn, 82.30.Rs, 82.33.Jx, 82.56.Ub, 82.75.-z, 88.30.R-
Adsorption of hydrogen by nanostructured microporous and mesoporous materials such as silicalite, zeolite, and activated carbon, modified by Pd nanoclusters, source silicalite, and ‘LiChrolut EN’ micromesoporous polymeric adsorbent is studied using 1H NMR spectroscopy under quasi-isobaric conditions at 200–283 K. As revealed, a certain amount of water enhances the adsorption of hydrogen by the factor 2–3. However, modification of the adsorbents with Pd does not increase the hydrogen adsorption. Silicalite with Pd clusters becomes too hydrophilic and, in contrast to the initial material, can absorb a lot of water. A model of co-adsorption of water and hydrogen in nanopores is developed. It explains an increase of the hydrogen adsorption in the presence of pre-adsorbed water by formation of secondary micropores in mesopores between the clusters or the domains of strongly associated water (SAW) and the pore walls. The main condition of enhanced adsorption of hydrogen is leaky binding of water clusters or SAW domains with the surface. Therefore, the effect of the increased adsorption of hydrogen disappears on highly hydrophilic surfaces (after modification by Pd).