Improvement of the hydrogen-storage kinetics of Mg by reactive mechanical grinding with 10 wt.% Fe2O3 and 5 wt.% Ni

Abstract

The addition of Fe2O3 to Mg is believed to be able to increase the hydriding rate of Mg, and the addition of Ni is thought to be able to increase the hydriding and dehydriding rates of Mg. A sample Mg-(10wt.%Fe2O3, 5 wt.%Ni) was prepared by mechanical grinding under H2 (reactive mechanical grinding). The as-milled sample absorbed 4.61 wt.% of hydrogen at 593 K under 12 bar H2 for 60 min. Its activation was accomplished after two hydriding-dehydriding cycles. The activated sample absorbed 4.59 wt.% of hydrogen at 593 K under 12 bar H2 for 60 min, and desorbed 3.83 wt.% hydrogen at 593 K under 1.0 bar H2 for 60 min. The activated Mg-(10wt.%Fe2O3, 5 wt.%Ni) had a slightly higher hydriding rate at the beginning of the hydriding reaction but a much higher dehydriding rate compared with the activated Mg-10 wt.%Fe2O3. prepared via spray conversion. After hydriding-dehydriding cycling, Fe2O3 was reduced, Mg2Ni was formed by the reaction of Mg with Ni, and a small fraction of Mg was oxidized.