Superior synergistic effect derived from MnTiO3 nanodiscs for the reversible hydrogen storage properties of MgH2

Herein, nanodisc-like MnTiO 3 was successfully prepared via a hydrothermal method , and for the first time, the MnTiO 3 nanodiscs were doped into magnesium hydride (MgH 2 ) for the study. In the first dehydrogenation cycle, MgH 2 -8 wt% MnTiO 3 showed a low onset hydrogen release temperature of 202 °C, while MnTiO 3 was transformed into Mg 6 MnO 8 and TiO x by reaction with MgH 2 , which played a real catalyst in the subsequent reaction. The composite system could instantly absorb 4.79 wt% H 2 in 100 s at 150 °C and rapidly release about 5.71 wt% H 2 in 500 s at 300 °C. The Kissinger plot revealed that the dehydrogenation activation energy dropped to 72.06 kJ/mol, which was significantly lower than that of as-milled MgH 2 . Moreover, after 50 isothermal cycles, the composite system still has an excellent capacity retention rate of 94.4 %. Compositional and structural analysis indicated that the in situ formation of TiO x and Mg 6 MnO 8 during dehydrogenation provided a multivalent multielement catalytic surrounding that accelerated the H atoms adsorption and dissociation, yielding a better kinetic property of MgH 2 .