Catalytic effects of subsurface carbon in the chemisorption of hydrogen on a Mg(0001) surface: an ab-initio study

Du, A.J., Smith, Sean C., Yao, X.D., and Lu, G.Q. (2006) Catalytic effects of subsurface carbon in the chemisorption of hydrogen on a Mg(0001) surface: an ab-initio study. Journal of Physical Chemistry Part B , 110 (4). pp. 1814-1819.

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Abstract

Ab initio density functional theory (DFT) calculations are performed to explore possible catalytic effects on the dissociative chemisorption of hydrogen on a Mg(0001) surface when carbon is incorporated into Mg materials. The computational results imply that a C atom located initially on a Mg(0001) surface can migrate into the subsurface and occupy an fcc interstitial site, with charge transfer to the C atom from neighboring Mg atoms. The effect of subsurface C on the dissociation of H2 on the Mg(0001) surface is found to be relatively marginal: a perfect sublayer of interstitial C is calculated to lower the barrier by 0.16 eV compared with that on a pure Mg(0001) surface. Further calculations reveal, however, that sublayer C may have a significant effect in enhancing the diffusion of atomic hydrogen into the sublayers through fcc channels. This contributes new physical understanding toward rationalizing the experimentally observed improvement in absorption kinetics of H2 when graphite or single walled carbon nanotubes (SWCNT) are introduced into the Mg powder during ball milling.

Item ID: 3669
Item Type: Article (Research - C1)
ISSN: 1520-5207
Keywords: Ab initio DFT; energy barrier; hydrogen dissociation; hydrogen storage; magnesium
Date Deposited: 27 Nov 2009 01:48
FoR Codes: 10 TECHNOLOGY > 1007 Nanotechnology > 100799 Nanotechnology not elsewhere classified @ 50%
SEO Codes: 85 ENERGY > 8506 Energy Storage, Distribution and Supply > 850699 Energy Storage, Distribution and Supply not elsewhere classified @ 40%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960606 Rights to Environmental and Natural Resources (excl. Water Allocation) @ 30%
85 ENERGY > 8598 Environmentally Sustainable Energy Activities > 859899 Environmentally Sustainable Energy Activities not elsewhere classified @ 30%
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