Catalytic effect of TiF4 in improving hydrogen storage properties of MgH2

The effect of TiF4 additive on the hydrogen sorption properties of MgH2 was investigated. MgH2 + x wt% TiF4 composites were prepared by ball milling and characterised for their structural, morphological and thermal properties. TGA studies show that MgH2 with x wt% TiF4 additive exhibit a lower onset desorption temperature compare to as-milled and pure MgH2. Activation energy measured by Kissinger plot for hydrogen desorption are estimated to be −171, −137, −76, −70, −77 kJ/mol for as-received, as-milled and MgH2 + xwt% TiF4 (x = 5,10,15). This indicates that activation energy is reduced by 101 kJ/mol and 67 kJ/mol for 10 wt% TiF4 added MgH2 as compared to as-received and milled MgH2. XRD and XPS studies were undertaken to characterize the phase changes during milling and dehydrogenation. The improvement in hydrogenation properties of MgH2 is due to formation of MgF2 that was formed during the dehydrogenation process. It is observed that the hydrogen sorption kinetics is markedly improved by TiF4 additive.