MoS<sub>2</sub>/TiO<sub>2</sub> Heterostructures In\nSitu Constructed on Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub> MXene for High-Rate and Stable

Out-of-plane ordered Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub> MXene is composed of M-site\nbinary metals\nwith richer structural compositions and physicochemical properties,\nthus becoming a potential candidate for energy storage materials.\nHere, the microstructures of pre-etched Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub> MXene were cleverly modified\nby the hydrothermal method at 250 °C and a sulfur-containing\natmosphere, while MoS<sub>2</sub>/TiO<sub>2</sub> heterostructures\nwere in situ constructed on Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub> MXene. The as-prepared Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub>@MoS<sub>2</sub>/TiO<sub>2</sub> hybrids deliver excellent lithium/sodium\nstorage properties, especially outstanding rate properties and robust\ncycling stability. At 5 A g<sup>–1</sup>, Mo<sub>2</sub>Ti<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub>@MoS<sub>2</sub>/TiO<sub>2</sub> provides reversible Li<sup>+</sup> (377.8 mAh g<sup>–1</sup>)/Na<sup>+</sup> (133.5 mAh g<sup>–1</sup>)\nstorage capacity. Capacity preservation reaches 83.7%/74% over 4500/30,000\ncycles in LIBs/SIBs. This paper highlights the importance of rational\nstructural modification by utilizing the rich metal compositions of\nM-sites in MXene, effectively enhancing its lithium/sodium storage\ncapacity and broadening the further application of double transition\nmetal MXene in secondary batteries.