Restricted dynamics of molecular hydrogen confined in activated carbon nanopores

被引：28

作者：

Contescu, Cristian I. ^{[1
]}

Saha, Dipendu ^{[1
]}

Gallego, Nidia C. ^{[1
]}

Mamontov, Eugene ^{[2
]}

Kolesnikov, Alexander I. ^{[2
]}

Bhat, Vinay V. ^{[1
]}

机构：

[1] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA

[2] Oak Ridge Natl Lab, Neutron Scattering Sci Div, Oak Ridge, TN 37831 USA

来源：

CARBON | 2012年 / 50卷 / 03期

基金：

美国能源部;

关键词：

INELASTIC NEUTRON-SCATTERING; TRANSLATIONAL DYNAMICS; SELF-DIFFUSION; SOLID HYDROGEN; PORE-SIZE; ADSORPTION; H-2; ZEOLITE; LIQUID; STORAGE;

D O I：

10.1016/j.carbon.2011.10.016

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: a carbon derived from polyfurfuryl alcohol and an ultramicroporous carbon. Fast, but incomplete ortho-para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 angstrom) were immobile below 22-25 K. Mobility increased rapidly with temperature above this threshold, which is higher than the melting point of bulk hydrogen (13.9 K). Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between similar to 22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H-2 confined in narrow nanopores. (C) 2011 Elsevier Ltd. All rights reserved.

引用

页码：1071 / 1082

页数：12

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