Catalytic effect of two-dimensional Mo2TiC2 MXene for tailoring hydrogen storage performance of MgH2

Two-dimensional Mo 2 TiC 2 MXenematerial was synthesized by etching Mo 2 TiAlC 2 and then doped into MgH 2 to tailor its hydrogen storage performance. The initial hydrogen desorption temperature of the Mo 2 TiC 2 -doped MgH 2 was significantly reduced from 330 °C (pristine MgH 2 ) to 187 °C. Isothermal dehydrogenation analysis indicated that the MgH 2 +9 wt.% Mo 2 TiC 2 composite rapidly discharged 6.4 wt.% H 2 at 300 °C within 4 min. For hydrogenation, the dehydrogenated MgH 2 +9 wt.% Mo 2 TiC 2 uptook 6.5 wt.% H 2 at 175 °Cwithin 5 min. By calculation, the activation energy for MgH 2 +9 wt.% Mo 2 TiC 2 was calculated to be (135.6±1.9) kJ/mol for the desorption reaction and (46.1±0.2) kJ/mol for the absorption reaction. After 20 cycles, 1.0 wt.% H 2 was lost for the MgH 2 +9 wt.% Mo 2 TiC 2 composite. Microstructure analysis results showed that the presence of Mo in Mo 2 TiC 2 enhanced the thermal stability of MXene and reduced the amount of active Ti during cycling, leading to poorer catalytic effect of the catalyst compared to Ti 3 C 2 .