Effect of Hydrogen Ion Flux for Reduction and Hydrogenation of Magnesium Oxide Using Microwave Excited Hydrogen Plasma

Sodium borohydride (NaBH 4 ) is attracting attention for regeneratable and large capacity hydrogen carrier. NaBH 4 generates sodium metaborate (NaBO 2 ) as by-product of dehydrogenation. Here, MgH 2 is important for regeneration from NaBO 2 to NaBH 4 with ball milling process and becomes Mg oxide after reaction. 1 The main purpose of this study is to reduce and hydrogenate the Mg oxide generated in the regeneration of NaBH 4 by using low-temperature microwave excited hydrogen plasma. In the plasma processing, atomic hydrogen (H) and ion (H + ) will contribute to Mg oxide reduction and hydrogenation. However, the dissociation of hydrogen from the hydrogenated Mg surface also occurs simultaneously. The dissociation of hydrogen is much dependent on the surface temperature of Mg, and the reduction rate of Mg oxides decreases at high temperature. Therefore, the effects of Mg surface temperature and ion bombardment which cause the increase in temperature are investigated.