Defect-Rich TiO2 In Situ Evolved from MXene for the Enhanced Oxidative Dehydrogenation of Ethane to Ethylene

Selective oxidative dehydrogenation (ODH) of light alkanes to alkenes over metal oxides usually obeys a redox catalysis cycle, where the release and recovery of lattice oxygen play a key role in catalytic performance. Therefore, it remains a challenge to prepare metal oxides with limited reducibility, such as TiO2, as a dominant active component rather than as a support or modifier in this process. Here, we find a significant increase of ethane ODH performance over a layered TiO2 (M-TiO2) catalyst, which is in situ evolved from a Ti3C2Tx MXene material during the reaction. The reactivity of this M-TiO2 is 4 times higher than that of P25 TiO2, with an excellent ethylene productivity of 15.4 g(C2H4) g(cat)(-1) h(-1) that outperforms the previously reported catalysts. Experimental characterizations and theoretical calculations reveal the importance of Ti and oxygen vacancy defects over M-TiO2 on the conversion of C2H6. The Ti vacancy sites can stabilize the defective structure and increase the reducibility of lattice oxygen to reduce the activation energy barrier of ethane, while the oxygen vacancy sites facilitate the activation of O-2 to recover lattice oxygen.