Atomically selective oxidation of (Ti,V) MXene to construct TiO2@TiVCTx heterojunction for high-performance Li-ion batteries

In situ derivation of TiO2 from Ti2CTx and Ti3C2Tx MXenes is a promising strategy to construct TiO2-based heterostructure. How to precisely control the conversion depth of MXene and well maintain its lamellar structure are the top priority. Herein, double transition metal (Ti, V) MXenes (Ti2-yVyCTx) act as precursors to engineer TiO2/MXene heterostructure as anode materials for lithium-ion batteries. Due to the different oxidation tendency, vanadium atoms with higher oxidative tolerance can maintain the 2D lamella morphology and high electronic conductivity while titanium atoms can be selectively oxidized to well-dispersed TiO2 nanoparticles. Moreover, the content and dispersity of derived TiO2 nanoparticles can be well controlled by adjusting the molar ratio of Ti/V in the Ti2-yVyCTx precursors. The intensive interfacial interaction between derived TiO2 and vanadium dominated MXene layers protects TiO2 nanoparticles from pulverization and detachment from 2D MXene as well as the restacking of MXene layers during charge/discharge cycles. Benefiting from the synergistic effects, the TiO2@TiVCTx anode delivers a superior specific capacity of 741.2 mAh g-1 at 0.1 A g-1, which shows prominent advantage in current MXene-derived anode materials. This work innovatively realizes atomically selective oxidation of double metal transition MXenes and regulate the derivatives for high performance anode materials.