Synthesis and hydrogen storage thermodynamics and kinetics of Mg(AlH4)2 submicron rods

Abstract

Abstract Mg(AlH 4 ) 2 submicron rods with 96.1% purity have been successfully synthesized in a modified mechanochemical reaction process followed by Soxhlet extraction. ∼9.0 wt% of hydrogen is released from the as-prepared Mg(AlH 4 ) 2 at 125–440 °C through a stepwise reaction. Upon dehydriding, Mg(AlH 4 ) 2 decomposes first to generate MgH 2 and Al. Subsequently, the newly produced MgH 2 reacts with Al to form a Al 0.9 Mg 0.1 solid solution. Finally, further reaction between the Al 0.9 Mg 0.1 solid solution and the remaining MgH 2 gives rise to the formation of Al 3 Mg 2 . The first step dehydrogenation is a diffusion-controlled reaction with an apparent activation energy of ∼123.0 kJ/mol. Therefore, increasing the mobility of the species involved in Mg(AlH 4 ) 2 will be very helpful for improving its dehydrogenation kinetics.