Engineering the Oxygen Vacancies in Na 2 Ti 3 O 7 for Boosting Its Catalytic Performance in MgH 2 Hydrogen Storage

Development of catalysts with highly efficient catalytic performance has a significant status in accelerating the MgH2 hydrogen storage system. In this work, we report a Na2Ti3O7 catalyst with rich oxygen vacancies (Na2Ti3O7-Ov), which was synthesized from Ti3C2-MXene, and confirm a remarkable enhancement to the hydrogen storage performance of MgH2. Expressly, the initial dehydrogenation temperature of the MgH2 + 5Na2Ti3O7-Ov (an addition of 5 wt % Na2Ti3O7-Ov) composite reduced substantially from 287 °C (for MgH2) to 183 °C. Additionally, the MgH2 + 5Na2Ti3O7-Ov composite presented fast hydrogen ab/desorption kinetics and excellent reversible hydrogen storage performance with a retention rate of 90.1% after 10 cycles. Both experimental and theoretical calculations data verified that the oxygen vacancies in Na2Ti3O7-Ov reduce the reaction activation energy during MgH2 dehydrogenation and then convey an excellent hydrogen storage kinetics. This work provides a new design for advanced defect-based nanocatalysts for the MgH2 hydrogen storage system.