Hamamelis-like K2Ti6O13 Synthesized by Alkali Treatment of Ti3C2 MXene: Catalysis for Hydrogen Storage in MgH2

An intriguing Hamamelis-like structure of K2Ti6O13 with branches of 10–20 nm in length is synthesized by alkali treatment of Ti3C2 MXene. It exhibits strong catalytic activity for hydrogen desorption from MgH2. The initial dehydrogenation temperature (175 °C) of a composite of MgH2 with 5 wt % K2Ti6O13 is 112 °C below that of pristine MgH2. Isothermal dehydrogenation analysis indicates that the composite releases 6.7 wt % hydrogen at 280 °C within 3 min, and with 2.7 wt % hydrogen being released at 200 °C. The activation energy of this material (105.67 kJ mol–1) is 69.67 kJ mol–1 lower than that of pristine MgH2. Its strong hydrogen adsorption/desorption capacity is attributed to the synergies of catalytic effects of KMgH3, TiO, and Ti, which originated from K2Ti6O13. These findings make a contribution to study the H2 storage properties of metal hydrides doped with Ti3C2 MXene derivatives.