Interfacial Engineering of Fluorinated TiO2 Nanosheets with Abundant Oxygen Vacancies for Boosting the Hydrogen Storage Performance of MgH2

The interaction between fluorinated surface in the partially reduced nano-crystallite titanium dioxide (TiO_2-x(F)) and MgH₂ is studied for the first time. Compared with pristine MgH₂ (416 °C), the onset desorption temperature of MgH₂+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 MgF₂ and MgF_2-xH_x is beneficial for improving the hydrogen storage performance of MgH₂. Moreover, oxygen vacancies can accelerate the electron transportation and facilitate hydrogen diffusion. The study provides a novel perspective on the modification of MgH₂ by fluorinated transition metal oxide catalyst.