High hydrogen storage capacity of nanosized magnesium synthesized by high energy ball-milling

Abstract To prepare nanosized magnesium which reversibly absorbs hydrogen with high capacity even under mild conditions, high energy ball-milling of Mg or MgH 2 with benzene or cyclohexane as additives have been studied. In ball-milling of Mg or MgH 2 , the use of the organic additives is very crucial in determining the characteristics of the resulting nanosized magnesium. Benzene and cyclohexane served to maintain the high-degree dispersion of nanostructured magnesium with small crystallite sizes (9–10 nm) and high surface areas (24–25 m 2 g −1 ). The behavior of hydrogen absorption by the magnesium was extensively evaluated by differential scanning calorimetry (DSC) measurements and volumetric techniques. The nanosized magnesium prepared by ball-milling of MgH 2 with benzene showed reversible DSC traces for hydriding/dehydriding under 0.1 MPa hydrogen pressure. Moreover, 1 at.% Al-doped or 2.9 at.% Ni-doped nanosized samples obtained by milling of MgH 2 with solutions of Al(C 2 H 5 ) 3 or Ni(C 5 H 5 ) 2 in benzene showed satisfying hydrogen absorption rates, respectively. The reversible hydrogen absorption by the 1 at.% Al-doped sample approximately reached a maximal capacity of 7.3 wt.% even at a 0.1 MPa H 2 atmosphere.