Catalytic effect of nano-particle 3d-transition metals on hydrogen storage properties in magnesium hydride MgH2 prepared by mechanical milling
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Hydrogen storage materials
We examined the catalytic effect of nano-particle 3d-transition metals on hydrogen desorption (HD) properties of MgH2 prepared by mechanical ball milling method. All the MgH2 composites prepared by adding a small amount of nano-particle Fenano, Conano, Ninano and Cunano metals and by ball milling for 2h showed much better HD properties than the pure ball-milled MgH2 itself. Especially, the 2 mol% Ninano-doped MgH2 composite prepared by soft milling for a short milling time of 15 min under a slow milling revolution speed of 200 rpm shows the most superior hydrogen storage properties: A large amount of hydrogen (~6.5 wt.%) is desorbed in the temperature range from 150 to 250 ºC at a heating rate of 5 ºC /min under He gas flow with no partial pressure of hydrogen. The EDX micrographs corresponding to Mg and Ni elemental profiles indicated that nano-particle Ni metals as catalyst homogeneously dispersed on the surface of MgH2. In addition, it was confirmed that the product revealed good reversible hydriding/dehydriding cycles even at 150 ºC. The hydrogen desorption kinetics of catalyzed and non-catalyzed MgH2 could be understood by a modified first order reaction model, in which the surface condition was taken into account.
Journal of Physics and Chemistry of Solids
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