Hydriding characteristics of Mg-based composites prepared using a ball mill

Mechanical milling of magnesium and 5 wt.% Pd-supporting graphite (5 wt.% Pd/G) in the presence of tetrahydrofuran (THF) gave rise to the formation of novel Mg-based composites (Mg/Pd/G) as effective hydrogen storage materials. The Mg-composite storage materials were extremely active toward hydrogen absorption even at 300 K and showed excellent reversibility for hydriding-dehydriding. The characteristics of the samples were investigated extensively in connection with the preparative conditions. In particular, the presence of THF strongly affected the hydriding properties of the resulting composites. Upon milling of Mg and Pd/G in the presence of THF the graphite layer structure was almost decomposed and the magnesium component was highly dispersed in the particle sizes of about 24-27 nm. The specific surface area of the samples increased to reach a value of 34-65 m(2) g(-1). The Mg-composites as a hydrogen storage material are those in which such a finely divided magnesium is in intimate contact with graphite containing synergism between Mg and aromatic carbons in graphite.