NiZnO Synthesised via a Solid-State Method for Promoting Hydrogen Sorption from MgH.

Magnesium hydrides (MgH) have drawn a lot of interest as a promising hydrogen storage material option due to their good reversibility and high hydrogen storage capacity (7.60 wt.%). However, the high hydrogen desorption temperature (more than 400 °C) and slow sorption kinetics of MgH are the main obstacles to its practical use. In this research, nickel zinc oxide (NiZnO) was synthesized via the solid-state method and doped into MgH to overcome the drawbacks of MgH. The onset desorption temperature of the MgH-10 wt.% NiZnO sample was reduced to 285 °C, 133 °C, and 56 °C lower than that of pure MgH and milled MgH, respectively. Furthermore, at 250 °C, the MgH-10 wt.% NiZnO sample could absorb 6.50 wt.% of H and desorbed 2.20 wt.% of H at 300 °C within 1 h. With the addition of 10 wt.% of NiZnO, the activation energy of MgH dropped from 133 kJ/mol to 97 kJ/mol. The morphology of the samples also demonstrated that the particle size is smaller compared with undoped samples. It is believed that in situ forms of NiO, ZnO, and MgO had good catalytic effects on MgH, significantly reducing the activation energy and onset desorption temperature while improving the sorption kinetics of MgH.