Magnesium nickel hydride monocrystalline nanoparticles for reversible hydrogen storage

Although Mg-based hydrides are extensively considered as a prospective material for solid-state hydrogen storage and clean energy carriers, their high operating temperature and slow kinetics are the main challenges for practical application. Here, a Mg–Ni based hydride, Mg₂NiH₄ nanoparticles (∼100 nm), with dual modification strategies of nanosizing and alloying is successfully prepared via a gas-solid preparation process. It is demonstrated that Mg₂NiH₄ nanoparticles form a unique chain-like structure by oriented stacking and exhibit impressive hydrogen storage performance: it starts to release H₂ at ∼170 °C and completes below 230 °C with a saturated capacity of 3.32 wt% and desorbs 3.14 wt% H₂ within 1800 s at 200 °C. The systematic characterizations of Mg₂NiH₄ nanoparticles at different states reveal the dehydrogenation behavior and demonstrate the excellent structural and hydrogen storage stabilities during the de/hydrogenated process. This research is believed to provide new insights for optimizing the kinetic performance of metal hydrides and novel perspectives for designing highly active and stable hydrogen storage alloys.