Synthesis of magnesium nanoparticles with superior hydrogen storage properties by acetylene plasma metal reaction

In this work, we developed a method to prepare ultrafine Mg nanoparticles around 40 nm by acetylene plasma metal reaction, which is a revised approach for the traditional hydrogen plasma metal reaction. During the preparation, the growth of the Mg nanoparticles was confined by the carbon from the decomposition of acetylene. The size of the Mg particles exhibited a clear decreasing trend with increasing acetylene fraction in the plasma. Due to the short diffusion distance and large specific surface area, the kinetics of hydrogenation and dehydrogenation of the small Mg nanoparticles were improved. From the equilibrium plateau pressures of the absorption and desorption isotherms, the enthalpy and entropy of the reaction were deduced, which were significantly reduced compared to the commercial magnesium.

► Acetylene was introduced into the arc plasma to control the growth of Mg particles.
► Mg nanoparticles around 40 nm were prepared by acetylene plasma metal reaction.
► The Mg particle size reduced with increasing the concentration of acetylene.
► The activation energy for the absorption and desorption of Mg were reduced.
► The reaction enthalpy and entropy were reduced.