Modifying the hydrogen storage performances of NaBH4 by catalyzing with MgFe2O4 synthesized via hydrothermal method

In this study, the hydrogenation performance of NaBH₄ was modified by the addition of 10 wt% MgFe₂O₄ as the catalyst. The NaBH₄ + 10 wt% of MgFe₂O₄ sample was prepared by a ball milling technique. The onset decomposition temperature of MgFe₂O₄-doped NaBH₄ was decreased to 323 °C and 483 °C for the first and second stage of dehydrogenation as compared to the milled NaBH₄ (497 °C). The desorption kinetics study showed that the addition of MgFe₂O₄ caused the sample to had faster hydrogen desorption with a capacity of 6.2 wt% within 60 min while the milled NaBH₄ had only released 5.3 wt% of hydrogen in the same period of time. For the isothermal absorption kinetics, the total amount of hydrogen absorbed by the milled NaBH₄ was 3.7 wt% while the NaBH₄ + 10 wt% MgFe₂O₄ sample showed better absorption characteristic with a total amount of 4.5 wt% of hydrogen within 60 min. The calculated desorption activation energy from the Kissinger plot of NaBH₄ + 10 wt% MgFe₂O₄ sample was 187 kJ/mol which reduced by 28 kJ/mol than the milled NaBH₄ (215 kJ/mol). The in-situ formation of MgB₆ and Fe₃O₄ after the dehydrogenation process indicates that these new species were responsible for the improved hydrogenation performances of NaBH₄.