(Ni–TiO2)@C-catalyzed hydrogen storage performance of a Mg–Ni–Y alloy with LPSO and ternary eutectic structure

Abstract

A Mg₉₃Ni_3.5Y_3.5 hydrogen storage alloy was prepared using a composition design approach with a protective covering agent method. A self-synthesized 1 wt% nano (Ni–TiO₂)@C catalyst was added by ball milling. The in situ formation of the endogenous long-period stacking ordered (LPSO) phase facilitated the catalytic decomposition of products after hydrogenation. The synergistic effect of the external and in situ endogenous catalysts enhanced the hydrogen absorption and desorption capacities, increased the reaction rate and lowered the temperature corresponding to the maximum hydrogen storage capacity. The composite material absorbed up to 6.39 wt% of hydrogen at 300 °C and 30 bar. Even at 100 °C, it absorbed 3.87 wt% of hydrogen within 2 hours. The enthalpies of formation for the materials Mg₉₃Ni_3.5Y_3.5 and Mg₉₃Ni_3.5Y_3.5 + (Ni–TiO₂)@C (with the added catalyst) were −53.96 and −55.04 kJ mol⁻¹ H₂, respectively. The corresponding hydrogen absorption activation energies were −34.14 and −39.51 kJ mol⁻¹ H₂. In addition, the material displayed excellent cycling stability after 100 cycles with the addition of the catalyst.