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

Abstract

AbstractThe interaction between fluorinated surface in the partially reduced nano‐crystallite titanium dioxide (TiO2‐x(F)) and MgH2 is studied for the first time. Compared with pristine MgH2 (416 °C), the onset desorption temperature of MgH2+5 wt.% TiO2‐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 MgF2‐xHx 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.