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.