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

Abstract Previous studies have shown that ferrites give a positive effect in improving the hydrogen sorption properties of magnesium hydride (MgH 2). In this study, another ferrite, i.e., BaFe 12 O 19 , has been successfully synthesised via the solid state method, and it was milled with MgH 2 to enhance the sorption kinetics. The result showed that the MgH 2 + 10 wt% BaFe 12 O 19 sample started to release hydrogen at about 270 °C which is about 70 °C lower than the as-milled MgH 2. The doped sample was able to absorb hydrogen for 4.3 wt% in 10 min at 150 °C, while as-milled MgH 2 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 °C, while the as-milled MgH 2 only released about 1.5 wt% of hydrogen. From the Kissinger plot, the apparent activation energy of the BaFe 12 O 19 -doped MgH 2 sample was 115 kJ/mol which was lower than the milled MgH 2 (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 MgH 2 for hydrogen storage. Highlights • BaFe 12 O 19 is synthesised via a solid state method. • BaFe 12 O 19 showed superior catalytic effects for MgH 2. • The decomposition temperature of BaFe 12 O 19 -doped MgH 2 reduced by 70 °C. • BaFe 12 O 19 -doped MgH 2 absorbs 4.3 wt% H 2 within 10 min at 150 °C. • The new species of MgO, Fe and Ba or Ba-containing play a synergistic role. [ABSTRACT FROM AUTHOR]