Effect of hydrogen ion dose and sample temperature on hydrogenation of Mg oxides using microwave excited hydrogen plasma

Abstract The aim of this study is to hydrogenate the magnesium oxides using microwave excited hydrogen plasma. Magnesium hydride (MgH 2 ) is important for a regeneration of sodium borohydride (NaBH 4 ) which is attracting attention for a regeneratable powdered hydrogen carrier. In the plasma processing, a hydrogen radical (H * ) and ion (H + ) will contribute to the hydrogenation of magnesium oxides. However, high temperature at the hydrogenated magnesium surface will cause dehydrogenation. Therefore, we investigated the effect of hydrogen ion dose and sample temperature T in the plasma treatment. As a result of XPS analysis, it was found that MgO was reduced into magnesium by the hydrogen ion dose. The reduced magnesium will support the hydrogenation. As a result of Raman spectroscopy, it was found that hydrogenation and growth of hydrogenated magnesium on the surface of the magnesium oxides require the ion and radical dose and T suppression.