Promoted hydrogen storage properties of MgH2 by Ti3+self-doped defect-mediated TiO2

Magnesium hydride (MgH2) has been expected as a promising solid material for efficiently storing hydrogen, but its practical applications have been impeded by stable thermodynamics and slow hydrogen desorption kinetics. In this study, we synthesized Ti3+ self-doped 3D TiO2 hollow nano-boxes (Ti3+@TiO2) through a facile hydrothermal reaction and investigated their influence on the hydrogen storage properties of MgH2. The abundant oxygen vacancies of Ti3+@TiO2 and the in-situ formed multivalent state of Ti-containing species during the de/ re-hydrogenation process resulted in an excellent catalytic effect on the hydrogen storage properties of MgH2. The BM-MgH2-Ti3+@TiO2-5 composite exhibited a low initial hydrogen desorption temperature of 205.4 degrees C, 49.2% reduction compared to pristine MgH2. The BM-MgH2-Ti3+@TiO2-5 composite could release 6.1 wt% of hydrogen at 325 degrees C within 20 min, and the activation energy (Ea) of dehydrogenation was decreased significantly to 57.2 & PLUSMN; 1.4 kJ/mol, achieving superior hydrogen desorption kinetics. In addition, this composite also demonstrated remarkable cycling stability, with hydrogen capacity retention of 93.7% after 10 consecutive de-/ rehydrogenated cycles at 325 degrees C. Our findings provide a new horizon for designing highly active catalysts for promoting the hydrogen storage properties of Mg-based materials.

Automated summary

In this study, Ti3+ self-doped 3D TiO2 hollow nano-boxes were synthesized and found to greatly improve the hydrogen storage properties of MgH2. The composite material exhibited a low initial desorption temperature and superior hydrogen desorption kinetics. It also demonstrated remarkable cycling stability.