Phase, microstructure and hydrogen storage properties of Mg-Ni materials synthesized from metal nanoparticles

After Mg and Ni nanoparticles were fabricated by hydrogen plasma metal reaction, Mg-rich MgxNi₁₀₀₋x(75 < x < 90) materials were synthesized from these metal nanoparticles to study the synergistic effects for hydrogen storage in these samples to show both good kinetics and high capacity. These MgxNi₁₀₀₋x materials may absorb hydrogen with a capacity of around 3.3-5.1 wt% in 1 min at 573 K. The Mg₉₀Ni₁₀ sample shows a hydrogen capacity of 6.1 wt%. The significant kinetic enhancement is thought to be due to the unique nanostructure from the special synthesis route, the catalytic effect of the Mg₂Ni nano phase, and the synergistic effects between the Mg₂Ni and Mg phases in the materials. An interesting phenomenon which has never been reported before was observed during pressure composition isotherm (PCT) measurements. One steep step in the absorption process and two obviously separated steps in the desorption process during PCT measurements of Mg₈₀Ni₂₀ and Mg₉₀Ni₁₀ samples were observed and a possible reason from the kinetic performance of the Mg₂Ni and Mg phases in absorption and desorption processes was explained. These MgxNi₁₀₀₋x materials synthesized from Mg and Ni nanoparticles show high capacity and good kinetics, which makes these materials very promising candidates for thermal storage or energy storage and utilization for renewable power.