Improvement in the hydrogen-storage properties of Mg by the addition of metallic elements Ni, Fe, and Ti, and an oxide Fe2O3

Pure Mg was employed as a starting material instead of MgH2 in this work. The magnesium prepared by mechanical grinding under H2 (reactive mechanical grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt.%. Ni, Fe and Ti were chosen as metallic transition elements to be added. Fe2O3 was selected as an oxide to be added. Samples Mg–14Ni–2Fe2O3–2Ti–2Fe were prepared by reactive mechanical grinding, and their hydrogen storage properties were examined and compared with those of a pure Mg sample prepared by reactive mechanical grinding under the same conditions. The Mg–14Ni–2Fe2O3–2Ti–2Fe sample showed much better hydrogen storage properties than the pure Mg sample. The as-milled Mg–14Ni–2Fe2O3–2Ti–2Fe sample did not require the activation. This sample absorbs 4.26 wt.% H for 5 min, and 4.41 wt.% H for 10 min, and 4.56 wt.% H for 60 min at n = 2. It desorbs 1.13 wt.% H for 10 min, 2.67 wt.% H for 30 min, and 3.32 wt.% H for 60 min at n = 2.

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► Additives’ content of about 20 wt.%, and use of pure Mg as a starting material.
► Addition of Ni, Fe, Ti, and Fe2O3.
► Formation of MgH2 during reactive mechanical grinding.
► Formation of Mg(OH)2 and Mg2NiH4 after hydriding–dehydriding cycling.
► Increase in the hydriding and dehydriding rates of Mg by the formation of Mg2NiH4.