Boosting effect of Fe–Ni/carbon material catalysts on the hydrogen storage performance of magnesium

Abstract

The low-cost, easily prepared metal Mg hydrogen storage materials are replacing Magnesium hydride (MgH2) as an attractive technology in energy storage applications. But the high hydrogen desorption temperature and sluggish hydrogen desorption kinetics behaviors hamper the application of Mg. Herein, Fe–Ni catalyst decorated carbon structure and three-dimensional graphene (3DG) as-prepared are incorporated into Mg powders by ball milling to improve the hydrogen storage performance. Mg2NiH4 produced by the reaction of MgH2 and Ni possesses a lower dehydrogenation enthalpy value than that of MgH2. Furthermore, carbon structure and 3DG provide more loading sites for metal particles and more channels for hydrogen diffusion. Consequently, the Mg+10 wt % FeNi@3DG composite can absorb 6.7 wt % H2 in 300 s (320 °C, 50 atm H2) and desorb 6.5 wt % in 180 s (320 °C, 0.5 atm H2 pressure) after the first hydrogenation/dehydrogenation process. In addition, the composite maintains a high hydrogen storage capacity after 6 cycles, demonstrating outstanding application prospects.