Catalytic Effect of Facile Synthesized TiH1.971 Nanoparticles on the Hydrogen Storage Properties of MgH2

Catalytic doping plays an important role in enhancing the hydrogen storage performance of MgH2, while finding an efficient and reversible catalyst remains to be a great challenge in enhancing the de/rehydrogenation properties of MgH2. Herein, a bidirectional nano-TiH1.971catalyst was prepared by a wet chemical ball milling method and its effect on hydrogen storage properties of MgH2was studied. The results showed that all the TiH1.971nanoparticles were effective in improving the de/rehydrogenation kinetics of MgH2. The MgH2composites doped with TiH1.971could desorb 6.5 wt % H2in 8 min at 300 °C, while the pure MgH2only released 0.3 wt % H2in 8 min and 1.5 wt % H2even in 50 min. It was found that the smaller the size of the TiH1.971particles, the better was the catalytic effect in promoting the performance of MgH2. Besides, the catalyst concentration also played an important role and the 5 wt %-c-TiH1.971modified system was found to have the best hydrogen storage performance. Interestingly, a significant hydrogen absorption amount of 4.60 wt % H2was evidenced for the 5 wt %-c-TiH1.971doped MgH2within 10 min at 125 °C, while MgH2absorbed only 4.11 wt% hydrogen within the same time at 250 °C. The XRD results demonstrated that the TiH1.971remained stable in cycling and could serve as an active site for hydrogen transportation, which contributed to the significant improvement of the hydrogen storage properties of MgH2.Keywords:hydrogen storage;MgH2;TiH1.971;catalytic effect;reversibility