Synthesis and hydrogen storage properties of Mg-10.6La-3.5Ni nanoparticles

The Mg-10.6 wt. % La-3.5 wt. % Ni nanoparticles are prepared by hydrogen plasma-metal reaction method. These nanoparticles are made of Mg, LaH ₃ and a small amount of Mg₂Ni. The as-prepared Mg nanoparticles of 180 nm are single crystalline and quasi-spherical in shape, and they change into polycrystalline after activation. LaH₃ and Mg ₂Ni nanoparticles are nearly spherical in shape with the mean particle size of 15 nm, and disperse on the surface of Mg. The Mg-10.6La-3.5Ni nanoparticles can absorb 3.2 wt. % H₂ in less than 15 min at 523 K and accomplish a high hydrogen storage capacity of 6.5 wt. % H₂ in less than 10 min at 673 K, almost reaching the theoretical gravimetric capacity. They can release 4.2 wt. % H₂ in 3 min at 623 K. The synergistic catalytic effect of LaH₃ and Mg₂Ni nanoparticles, the nanostructure and the low oxide content of Mg nanoparticles promote the hydrogen sorption process with the low hydrogen absorption activation energy of 39.1 kJ mol^-1.