Preparation and hydriding properties of magnesium-containing hydrogen storage materials chemically deposited from a homogeneous phase

Use of the dissolution of magnesium metal in liquid ammonia enabled novel magnesium-containing hydrogen storage materials to be prepared. The dispersion of magnesium atoms in ammonia matrices at 77 K using a metal vapour technique gave rise to a homogeneous solution of dissolved magnesium metal in liquid ammonia. Hydrogen storage materials prepared using the solvent power of ammonia are of two types. (i) Magnesium was crystallized out of the solution of dissolved magnesium in liquid ammonia; the crystallization was carried out in the presence or absence of catalytically active nickel powders (respectively Mg-Ni or Mg); (ii) Magnesium was highly dispersed on an active carbon (AC) support by impregnating the AC with the solution (referred to as $\text{Mg}\text{AC}$). Using AC on which catalytically active nickel had been previously supported, the preparation of samples was further extended to include binary systems ($\text{Mg-}\text{Ni}\text{AC}$). These samples were investigated in connection with the preparation methods. The magnesium samples were extremely active toward hydrogen absorption. For the Mg-Ni and $\text{Mg-}\text{Ni}\text{AC}$ samples an increase in nickel markedly accelerated the initial hydriding rates of the parent magnesium metal.