Improvement in the hydrogen-storage properties of Mg by the addition of metallic elements Ni, Fe, and Ti, and an oxide Fe 2O 3

Abstract

Pure Mg was employed as a starting material instead of MgH 2 in this work. The magnesium prepared by mechanical grinding under H 2 (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. Fe 2O 3 was selected as an oxide to be added. Samples Mg–14Ni–2Fe 2O 3–2Ti–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–2Fe 2O 3–2Ti–2Fe sample showed much better hydrogen storage properties than the pure Mg sample. The as-milled Mg–14Ni–2Fe 2O 3–2Ti–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.