Hydrogen Sorption Behaviors of a Core–Shell Structured Mg@Fe Composite Powder

Abstract

In the present work, a Fe covered pure Mg ultrafine powder–Mg@Fe- was prepared through electroless plating of Fe on the arc plasma evaporated Mg powder in a FeCl₃ n-butyl alcohol solution. The phase components, microstructure and hydrogen sorption behaviors of the Mg@Fe composite powder were investigated using XRD, TEM and PCT techniques. TEM observations revealed that those ultrafine Mg particles were covered by nano α-Fe grains reduced by Mg during electroless plating. The hydrogenation enthalpy of the Mg@Fe composite is determined to be −78 kJ/mol H₂ based on PCT measurements. Meanwhile, the hydrogen absorption activation energy of Mg@Fe composite is reduced to 54.6 kJ/mol H₂ and the onset desorption temperature of hydrogenated Mg@Fe is lower down to 620 K when compared to those for pure Mg powder. The improved hydrogen sorption kinetic properties of Mg@Fe composite over pure Mg powder can be mainly attributed to the catalytic effects from nano α-Fe covered on the Mg ultrafine particles.