In situ formation of highly dispersed LaH3 and Mg2Ni derived from 3DOM LaNiO3 for the hydrogen storage kinetics enhancement of MgH2

(3DOM) LaNiO 3 catalysts were successfully synthesized and significantly improved the hydrogen storage kinetics of MgH 2 . MgH 2 -5 wt% 3DOM LaNiO 3 can rapidly absorb 5.91 wt% H 2 at 175 °C within 500 s and desorb 6.37 wt% H 2 within 500 s at 300 °C, its hydrogen absorption and desorption rates are 10 and 11 times higher than MgH 2 -5 wt% Nano LaNiO 3 , respectively. This remarkable enhancement is primarily due to its unique 3DOM structure and the synergistic effect of highly dispersed LaH 3 and Mg 2 Ni/Mg 2 NiH 4 formed in situ during the ball milling and first de/re-hydrogenation process. 3DOM structure catalysts are fragile which can make the catalyst distribution more uniform during ball milling process, giving rise to the significantly improved catalytic activity. The theoretical calculation results show that Mg 2 Ni/LaH 3 heterostructure can greatly reduce the hydrogen adsorption energy to −0.768 eV and the heterogeneous interface induces the charge redistribution between Mg 2 Ni and LaH 3 , resulting in a small amount of negative charge accumulating on the surface of Mg 2 Ni. Moreover, highly dispersed LaH 3 and Mg 2 Ni/Mg 2 NiH 4 in the MgH 2 matrix create a multiphase interface, which can provide more active sites and a variety of pathways for hydrogen diffusion. Above reasons contribute to the excellent synergistic catalytic performance of in situ formed LaH 3 and Mg 2 Ni/Mg 2 NiH 4 on MgH 2 . These discoveries hold scientific value for the design and preparation of highly active catalysts using 3DOM materials for hydrogen storage in light-metal hydrides, especially in MgH 2 .