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Catalysts 2012, 2(3), 330-343; doi:10.3390/catal2030330
Article

Superior MgH2 Kinetics with MgO Addition: A Tribological Effect

1
 and 2,*
Received: 17 July 2012; in revised form: 26 July 2012 / Accepted: 31 July 2012 / Published: 13 August 2012
(This article belongs to the Special Issue Bimetallic Catalysts—Application in Hydrogen Storage)
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Abstract: The kinetics of hydrogen absorption/desorption in magnesium can be improved without any catalysis assistance and MgO was found to be more effective than the best catalyst reported so far, i.e., Nb2O5. Herein, a quantitative analysis of the hydrogen kinetics in magnesium modified with MgO was performed in order to identify possible rate controlling mechanisms. While hydrogen absorption was found to be diffusion controlled as commonly reported, hydrogen desorption evolved from nucleation and growth to an interface controlled process depending on the desorption temperature. Comparison with the effect of Nb2O5 indicates that similar rate limiting steps occur regardless of the oxide additive. These findings are reconciled by considering the tribological effect of solid oxide additives, as a correlation between oxides electronegativity and improvement in hydrogen kinetics was found. Such a correlation clearly highlights the mechanical effect of solid oxides in facilitating the grinding and stabilisation of small magnesium particles for efficient and fast hydrogen kinetics.
Keywords: magnesium; hydrogen storage; metal oxides; lubricious oxides; electronegativity; tribology magnesium; hydrogen storage; metal oxides; lubricious oxides; electronegativity; tribology
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Ares-Fernández, J.-R.; Aguey-Zinsou, K.-F. Superior MgH2 Kinetics with MgO Addition: A Tribological Effect. Catalysts 2012, 2, 330-343.

AMA Style

Ares-Fernández J-R, Aguey-Zinsou K-F. Superior MgH2 Kinetics with MgO Addition: A Tribological Effect. Catalysts. 2012; 2(3):330-343.

Chicago/Turabian Style

Ares-Fernández, José-Ramón; Aguey-Zinsou, Kondo-Francois. 2012. "Superior MgH2 Kinetics with MgO Addition: A Tribological Effect." Catalysts 2, no. 3: 330-343.


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