Room Temperature Hydrogen Absorption of Mg/MgH2 Catalyzed by BaTiO3

This paper seeks to present notable insights into the catalytic behavior of a ferroelectric BaTiO3 nanomaterial at the boundary plane in the separation of MgH2 starting from 185 °C. The synergy between mechanical milling and enhanced electronic distribution at the surface of BaTiO3 aided magnesium to a remarkable absorption of 4.5 wt % H2 at room temperature under 30 bar within 20 h. The composite released H2 ∼ 5.7 wt % in 15 min at 310 °C and ∼5.1 wt % in 90 min at 250 °C. The lowered activation energy of decomposition was calculated to be ∼60 kJ/mol with a decomposition enthalpy of 72.3 kJ/mol-H2. The composite reversibly produced ∼5.7 wt % H2 across 20 cycles in less than 120 h at 300 °C. As revealed by detailed experimental results, the interplay between +4 and +3 states of titanium at “111” twin boundaries of BaTiO3, and the formation of oxygen vacancies, play an important role in improving the sorption kinetics and the reversibility of Mg/MgH2. Meanwhile, the anomalous ferroelectric character of the +2 state of barium around Ti–O and Mg after milling of BaTiO3 is also believed to slightly enhance MgH2 desorption enthalpy via a chemisorption process. Our findings have brought MgH2 a few steps closer to practical applications.