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The influence of dispersion interactions on the hydrogen adsorption properties of expanded graphite.
MedLine Citation:
PMID:  23032350     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
We demonstrate the importance of London dispersion forces in defining the adsorption capacity within expanded graphite, a simple model of the more complex experimental geometries of activated carbon, using a combination of the non-local correlation functional of Dion et al paired with a recent exchange functional of Cooper (vdW-DF(C09x)) and a classical continuum model. Our results indicate that longer ranged interactions due to dispersion forces increase the volume over which molecules interact with a porous medium. This significantly enhances the adsorption density within a material, and explains recent experimental work showing that the densification of H(2) in carbon nanopores is sensitive to the pore size. Remarkably, our slit pore geometries give adsorption densities of up to 3 wt% at 298 K and 20 MPa which correlates well with experimental values for 9 Å pores-a value that could not be predicted using local density approximation (LDA) calculations. In its entirety, this work presents a powerful approach for assessing molecular uptake in porous media and may have serious impacts on efforts to optimize the properties of these materials.
Authors:
Yungok Ihm; Valentino R Cooper; Lujian Peng; James R Morris
Publication Detail:
Type:  Journal Article     Date:  2012-10-03
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  24     ISSN:  1361-648X     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  England    
Other Details:
Languages:  eng     Pagination:  424205     Citation Subset:  IM    
Affiliation:
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA.
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