Synergistic Effects of In-Situ-Formed Multivalent Titanium and Mg2Ni for Improving the Hydrogen-Storage Properties of MgH2

Abstract

Magnesium hydride (MgH2) 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 NiTiO3 nanoparticles smaller than 20 nm. Next, we investigated the effect of the NiTiO3 nanoparticles for educating the hydrogen storage performance of MgH2. The synergistic catalytic effect of multivalent titanium and Mg2Ni/Mg2NiH4 enhanced hydrogen storage performance of the MgH2 system. The addition of 5 wt % NiTiO3 lowered the initial hydrogen evolution temperature of MgH2 to 194 °C. After 12 minutes at 275 °C, the 5 wt % NiTiO3-MgH2 composites released 6.1 wt % of hydrogen. The dehydrogenation activation energy (Ea) of the 5 wt % NiTiO3-MgH2 composites decreased significantly to 38.78±2.1 kJ/mol. Furthermore, hydrogen uptake of 5 wt % NiTiO3-MgH2 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 MgH2.