Superior synergistic effect derived from MnTiO3 nanodiscs for the reversible hydrogen storage properties of MgH2
Chao Ma, Baozhou Zhao, Jianguang Yuan, Yunfeng Zhu, Jiguang Zhang, Bogu Liu, Ying Wu, Liquan Li, Shaoxiong Zhou
Abstract
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 .