The enhanced hydrogen storage performance of (Mg–B–N–H)-doped Mg(NH2)–2LiH system

Doping Mg(NH2)2–2LiH by Mg2(BH4)2(NH2)2 compound exhibits enhanced hydrogen de/re-hydrogenation performance. The peak width in temperature-programmed desorption (TPD) profile for the Mg(NH2)2–2LiH–0.1Mg2(BH4)2(NH2)2 was remarkably shrunk by 60 °C from that of pristine Mg(NH2)2–2LiH, and the peak temperature was lowered by 12 °C from the latter. Its isothermal dehydrogenation rate was greatly improved by five times from the latter at 200 °C. XRD, FTIR and NMR analyses revealed that a series of reactions occurred in the dehydrogenation of the composite. The prior interaction between LiH and Mg–B–N–H yielded intermediate LiBH4, which subsequently reacted with Mg(NH2)2 and LiH in molar ratio of 1:6:9 to form Li2Mg2(NH)3 and Li4BN3H10 phases. The observed 6Mg(NH2)2–9LiH–LiBH4 combination dominated the hydrogen release and soak in the composite system, and enhanced the kinetics of the system.