Electron oriented injection TiSe2-C laminated heterojunctions derived from terminal functionalized MXene for high-rate sodium ion storage

Herein, TiSe2-C laminated heterojunction in situ derived from halogen ion (-Cl, -F) terminal functionalized Ti3C2Tx MXene was prepared by the solid-state reaction. Functional precursor of Cl-enriched MXene was synthesized by chloride molten etching method, and high-crystalline TiSe2-C laminated heterojunction was obtained after the selenylation process. For F-enriched MXene, abundant TiO2 nanoparticles could be acquired besides TiSe2-C lamination. Based on DFT calculation results, the byproduct TiO2 and amorphous carbon can continuously inject electrons to TiSe2, owing to the discrepancy of work functions. Excellent charge-carrier transportation peculiarity gives TiSe2-C lamination heterojunction excellent electrochemical performances and can also accelerate the kinetic process. Among them, TiSe2-Cl demonstrates a reversible capacity of 369.14 mA h g(-1) at a current of 1 A g(-1) and even keeps a high rate capacity of 372.26 mA h g(-1) at 5 A g(-1). This study provides a new idea to synthesize MXene derivatives for high performance sodium ion batterry anode materials.