Enhanced hydrogen storage kinetics of MgH by the synergistic effect of MnO/ZrO nanoparticles.

As an ideal material for solid-state hydrogen storage, magnesium hydride (MgH) has attracted enormous attention due to its cost-effectiveness, abundant resources, and outstanding reversibility. However, the high thermodynamics and poor kinetics of MgH still hinder its practical application. In this work, a simple stirring-hydrothermal method was used to successfully prepare bimetallic MnO/ZrO nanoparticles, which were subsequently doped into MgH by mechanical ball milling to improve its hydrogen sorption performance. The MgH + 10 wt% MnO/ZrO composite began discharging hydrogen at 219 °C, which was 111 °C lower compared to the as-synthesized MgH. At 250 °C, the MgH + 10 wt% MnO/ZrO composite released 6.4 wt% hydrogen within 10 min, whereas the as-synthesized MgH reluctantly released 1.4 wt% hydrogen even at 335 °C. Moreover, the dehydrogenated MgH + 10 wt% MnO/ZrO sample started to charge hydrogen at room temperature. 6.0 wt% hydrogen was absorbed when heated to 250 °C under 3 MPa H pressure, and 4.1 wt% hydrogen was taken up within 30 min at 100 °C at the same hydrogen pressure. In addition, compared with the as-synthesized MgH, the de/rehydrogenation activation energy values of the MgH + 10 wt% MnO/ZrO composite were decreased to 64.52 ± 13.14 kJ mol and 16.79 ± 4.57 kJ mol, respectively, which incredibly contributed to the enhanced hydrogen de/absorption properties of MgH.