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

Abstract

Herein, TiSe₂–C laminated heterojunction in situ derived from halogen ion (–Cl, –F) terminal functionalized Ti₃C₂T_x 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.