Catalytically Enhanced Hydrogen Storage Properties of Mg(NH2)2+2LiH Material by Graphite-Supported Ru Nanoparticles

Identification of effective catalyst has been a subject of great interest and challenge in developing metal-N-H systems as potential hydrogen storage media. Motivated by the mechanistic understanding of the essential amide/imide conversion, we experimentally examined the possibility of N-H bond activation by using metal catalyst. We prepared the graphite-supported Ru nanoparticles (Ru/C catalyst) and evaluated their effect on the hydrogen storage properties of Mg(NH2)(2) + 2LiH material. Our studies show that the Ru/C catalyst is catalytically active toward both dehydrogenation and rehydrogenation reactions of Mg(NH2)(2) + 2LiH. Moreover, the catalytically enhanced hydrogen sorption kinetics persists well over 10 de/rehydrogenation cycles. Careful examination of the isothermal dehydrogenation behaviors suggests that the enhanced dehydrogenation kinetics may result from the Ru-catalyzed interface reaction between amide and imide solid phases. This is consistent with the Fourier transform infrared results, which show clearly the promoting effect of Ru catalyst on the N-H bond reconstruction. Finally, the catalytic mechanism of Ru catalyst on the reversible dehydrogenation reactions of Mg(NH2)(2) + 2LiH material is discussed.