Catalytic effect of (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 on hydrogen storage properties of ultrafine magnesium particles

In order to improve hydrogen storage properties of magnesium, (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 (TiMn₂ type) alloy particles have been added into magnesium ultrafine particles produced by a hydrogen plasma-metal reaction approach by ball milling. The (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 particles are uniformly dispersed on the surface of magnesium. The addition of (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 alloy improves both the hydrogen storage capacity and kinetics of magnesium. The magnesium-5 wt% (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 composite can absorb 6.00 wt% H₂ within 60 minutes at 523 K and desorb 6.00 wt% H₂ within 15 minutes at 623 K. With the increase of (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1, the hydrogenation and dehydrogenation kinetics of the composites improve. The apparent activation energies of magnesium-x wt% (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 (x = 5, 10, 30) composites for hydrogen absorption and desorption are 67.52, 65.80, 60.99 kJ mol^-1 and 121.37, 116.68, 77.25 kJ mol^-1, respectively. The enhanced hydrogen storage capacities and kinetics can be attributed to the effective catalysis of the (Ti_0.85Zr_0.15)_1.05Mn_1.2Cr_0.6V_0.1Cu_0.1 alloy and ultrafine size of magnesium particles.