De-hydrogenation/Rehydrogenation Properties and Reaction Mechanism of AmZn(NH2)n-2nLiH Systems (A = Li, K, Na, and Rb)

Sustainability 14(3), 1672 (2022). doi:10.3390/su14031672
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$_m$Zn(NH$_2$)$_n$ (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$_m$Zn(NH2)$_n$-2nLiH (with m = 2, 4 and n = 4, 6), as well as Na$_2$Zn(NH$_2$)$_4$∙0.5NH$_3$-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, Rb$_2$Zn(NH$_2$)$_4$-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.
Published by MDPI, Basel