High-efficiency hydrogen storage of magnesium hydride achieved by catalytic doping with zirconium titanate

Facing the bottlenecks of slow hydrogen liberation rate and elevated dehydrogenation temperature of magnesium hydride (MgH 2 ) in practical applications, researchers have accomplished in-depth and extensive studies, aiming at finding effective solutions to promote its hydrogen storage performance. In this work, zirconium titanate (ZrTiO 4 ) consisting of transition metal elements of Ti and Zr was prepared by hydrothermal synthesis, which could significantly improve the hydrogen storage performance of MgH 2 . The introduction of 7 wt% of ZrTiO 4 into MgH 2 by mall milling could reduce the beginning dehydrogenation temperature to 178.8 °C, which was 70 °C lower compared to ball-milled pristine MgH 2 (248.8 °C). Moreover, the MgH 2 –7 wt% ZrTiO 4 composite released 6.3 wt% of H 2 at 300 °C in 5 min and absorbed 5.5 wt% of H 2 at 125 °C in 10 min. The use of ZrTiO 4 as a catalyst displayed superior catalytic effects compared to the addition of TiO 2 or ZrO 2 alone. What is more important, the activation energy for dehydrogenation of MgH 2 –7 wt% ZrTiO 4 was greatly reduced by 29.7 % compared to that of ball-milled MgH 2 . The enhancement of the hydrogen storage properties of MgH 2 was ascribed to the in situ generation of MgTiO 3 and metal Zr from the reaction of ZrTiO 4 and MgH 2 during cycling dehydrogenation/rehydrogenation tests, which created a multivalent and multielement chemical environment that dramatically improved the hydrogen storage properties of MgH 2 . The results not only strongly confirm the significant value of the bimetallic catalytic effect in improving the hydrogen storage performance of MgH 2 , but also open up a new material design idea for the development of Mg-based solid-state materials for hydrogen storage.