Preparation and hydrogen sorption properties of a Ni decorated Mg based Mg@Ni nano-composite

摘要

For the first time, a nano Ni decorated Mg ultrafine powder, Mg@Ni nano-composite powder, was prepared through arc plasma evaporation of pure Mg followed by the elec-troless plating of Ni on the Mg ultrafine particles in a NiCl_2 solution. The phase components, microstructure and hydrogen sorption properties of the Mg@Ni composite powder were carefully investigated. It is observed that the composite is mainly composed of ultrafine Mg particles decorated by nano Ni grains introduced during electroless plating. Based on the Pressure-Composition-Temperature measurements, the hydrogenation enthalpy of the Mg@Ni composite is determined to be -73.6 kJ/mol H_2, close to that of pure Mg. Meantime, the hydrogen absorption kinetics can be improved and the hydrogen desorption temperature of the hydrogenated Mg@Ni nano-composite can be reduced as compared to those of the pure Mg ultrafine powder. The improved hydrogen sorption properties can be mainly attributed to the gateway effects from the Mg_2Ni/Mg_2NiH_4 phases formed on Mg/MgH_2 ultrafine particles after reVdehydrogenation cycles. The results showed that through arc plasma method followed by electroless plating of transition metals, the hydrogen storage properties of Mg ultrafine powders can be effectively improved.