Interfacial Engineering of Fluorinated TiO 2 Nanosheets with Abundant Oxygen Vacancies for Boosting the Hydrogen Storage Performance of MgH 2 .

The interaction between fluorinated surface in the partially reduced nano-crystallite titanium dioxide (TiO 2-x (F)) and MgH 2 is studied for the first time. Compared with pristine MgH 2 (416 °C), the onset desorption temperature of MgH 2 +5 wt.% TiO 2-x (F) composite can be dramatically lowered to 189 °C. In addition, the composite exhibits remarkable dehydrogenation kinetics, which can release 6.0 wt.% hydrogen thoroughly within 6 min at 250 °C. The apparent activation energy for dehydriding is decreased from 268.42 to 119.96 kJ mol -1 . Structural characterization and theoretical calculations indicate that the synergistic effect between multivalent Ti species, and the in situ formed MgF 2 and MgF 2-x H x is beneficial for improving the hydrogen storage performance of MgH 2 . Moreover, oxygen vacancies can accelerate the electron transportation and facilitate hydrogen diffusion. The study provides a novel perspective on the modification of MgH 2 by fluorinated transition metal oxide catalyst.