Synergistic Effects of In-Situ-Formed Multivalent Titanium and Mg2Ni for Improving the Hydrogen-Storage Properties of MgH2
Graphical We employ a hydrothermal method and high-temperature calcination to prepare well-dispersed NiTiO 3 nanoparticles with smaller than 20 nm. The NiTiO 3 nanoparticles show good catalytic effect on hydrogen storage of MgH 2 . The further structural analysis shows that the excellent hydrogen storage performance of MgH 2 -NiTiO 3 benefits from multivalent state of titanium and Mg 2 Ni/Mg 2 NiH 4 . Magnesium hydride (MgH 2 ) has gained significant consideration as a cost-effective solid-state hydrogen-storage material with a substantial hydrogen capacity. However, its practical applications are impeded by its poor kinetics and high thermal stability. In this study, we employed a hydrothermal method and high-temperature calcination to prepare well-dispersed NiTiO 3 nanoparticles smaller than 20 nm. Next, we investigated the effect of the NiTiO 3 nanoparticles for educating the hydrogen storage performance of MgH 2 . The synergistic catalytic effect of multivalent titanium and Mg 2 Ni/Mg 2 NiH 4 enhanced hydrogen storage performance of the MgH 2 system. The addition of 5 wt % NiTiO 3 lowered the initial hydrogen evolution temperature of MgH 2 to 194 °C. After 12 minutes at 275 °C, the 5 wt % NiTiO 3 -MgH 2 composites released 6.1 wt % of hydrogen. The dehydrogenation activation energy ( E a ) of the 5 wt % NiTiO 3 -MgH 2 composites decreased significantly to 38.78±2.1 kJ/mol. Furthermore, hydrogen uptake of 5 wt % NiTiO 3 -MgH 2 at 125 °C reaches 5.1 wt % in 300 s under hydrogen pressure of 20 bar. These findings introduce an innovative concept for preparing high active catalysts for improving the dehydrogenation/hydrogenation kinetics of MgH 2 .
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