Synthesis of BaFe12O19 by solid state method and its effect on hydrogen storage properties of MgH2

Previous studies have shown that ferrites give a positive effect in improving the hydrogen sorption properties of magnesium hydride (MgH2). In this study, another ferrite, i.e., BaFe12O19, has been successfully synthesised via the solid state method, and it was milled with MgH2 to enhance the sorption kinetics. The result showed that the MgH2 + 10 wt% BaFe12O19 sample started to release hydrogen at about 270 degrees C which is about 70 degrees C lower than the as-milled MgH2. The doped sample was able to absorb hydrogen for 4.3 wt% in 10 min at 150 degrees C, while as-milled MgH2 only absorbed 3.5 wt% of hydrogen under similar conditions. The desorption kinetic results showed that the doped sample released about 3.5 wt% of hydrogen in 15 min at 320 degrees C, while the as-milled MgH2 only released about 1.5 wt% of hydrogen. From the Kissinger plot, the apparent activation energy of the BaFe12O19-doped MgH2 sample was 115 kJ/mol which was lower than the milled MgH2 (141 kJ/mol). Further analyses demonstrated that MgO, Fe and Ba or Ba-containing contribute to the improvement by serving as active species, thus enhancing the MgH2 for hydrogen storage. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.