De-hydrogenation/Rehydrogenation Properties and Reaction Mechanism of A m Zn(NH 2) n -2 n LiH Systems (A = Li, K, Na, and Rb).

With the aim to find suitable hydrogen storage materials for stationary and mobile applications, multi-cation amide-based systems have attracted considerable attention, due to their unique hydrogenation kinetics. In this work, A_mZn(NH₂)_n (with A = Li, K, Na, and Rb) were synthesized via an ammonothermal method. The synthesized phases were mixed via ball milling with LiH to form the systems A_mZn(NH₂)_n-2nLiH (with m = 2, 4 and n = 4, 6), as well as Na₂Zn(NH₂)₄∙0.5NH₃-8LiH. The hydrogen storage properties of the obtained materials were investigated via a combination of calorimetric, spectroscopic, and diffraction methods. As a result of the performed analyses, Rb₂Zn(NH₂)₄-8LiH appears as the most appealing system. This composite, after de-hydrogenation, can be fully rehydrogenated within 30 s at a temperature between 190 °C and 200 °C under a pressure of 50 bar of hydrogen. [ABSTRACT FROM AUTHOR]