Enhanced reversible hydrogen storage properties of a Mg–In–Y ternary solid solution

A Mg(In, Y) ternary solid solution was successfully synthesized by two-step method, namely sintering the elemental powders and subsequent milling. The formation of Mg(In, Y) indicates that the solubility of Y in the Mg lattice is expanded due to the existence of In. The as-synthesized Mg90In5Y5 solid solution transformed to MgH2, YH3, In3Y and MgIn compound upon hydrogenation, the hydrogenated products except for the YH3 recovered to Mg(In, Y) solid solution after dehydrogenation. The Mg90In5Y5 solid solution exhibited a decreased reaction enthalpy of 62.9 kJ/(mol H2), reduction by ca. 5 kJ/(mol H2) or 12 kJ/(mol H2) than the Mg95In5 binary solid solution and pure Mg, respectively. The working temperature as well as the activation energies for the hydriding and dehydriding were also decreased in comparison with those of Mg(In) binary solid solution, which are attributed to the reduced reaction enthalpy and the catalytic role of YH3. Our work indicates that the thermodynamic and kinetic tuning of MgH2 are realized in the Mg(In, Y) ternary solid solution.