Mg-based hydrogen storage materials with improved hydrogen sorption

摘要

Nanocrystalline MgH{sub}2/Me{sub}xO{sub}y composite powders were produced by high energy ball milling (Me{sub}xO{sub}y = Sc{sub}2O{sub}3, TiO{sub}2, V{sub}2O{sub}5, Cr{sub}2O{sub}3, Mn{sub}2O{sub}3, Fe{sub}3O{sub}4, CuO, Al{sub}2O{sub}3, SiO{sub}2). The hydrogen absorption and desorption kinetics were determined in view of a technical application. The addition of selected oxides lead to an enormous catalytic acceleration of hydrogen sorption compared to pure nanocrystalline hydrides. In absorption, the catalytic effect of TiO{sub}2, V{sub}2O{sub}5, Cr{sub}2O{sub}3, Mn{sub}2O{sub}3, Fe{sub}3O{sub}4, and CuO is comparable. Concerning desorption, the composite material containing Fe{sub}3O{sub}4 shows the fastest kinetics followed by V{sub}2O{sub}5, Mn{sub}2O{sub}3, Cr{sub}2O{sub}3 and TiO{sub}2. Only 0.2 mol% of the catalysts is sufficient to provide a fast sorption kinetics. Additionally, Mg absorbs hydrogen already at room temperature by the use of metal oxides as catalysts. Furthermore, it is demonstrated for the first time that MgH{sub}2/Me{sub}xO{sub}y-powders release hydrogen at 200℃.