Electromagnetic interference shielding of Ti3C2Tx MXene modified by ionic liquid for high chemical stability and excellent mechanical strength

Ti3C2Tx MXene with two-dimensional (2D)-layered structure shows potential application in various fields owing to its superb metallic conductivity and excellent solution processability. However, a fundamental challenge limiting the implementation of Ti3C2Tx in practical applications is its susceptibility to oxidation in either humid or aqueous environments only within a few days, which results in the disassembly of the 2D-layered structure and severely deteriorates the functional properties including electrical conductivity, mechanical strength and EMI shielding performance. Herein, we firstly demonstrate a robust procedure to protect sensitive Ti3C2Tx from degradation by modification with imidazolium-based inion liquid (IL), which remarkably improves the chemical stability of Ti3C2Tx in aqueous and significantly increases the mechanical strength of assembled freestanding Ti3C2Tx film (IL-MXene). The crystalline structure of IL-MXene sheet remains intact up to 30 days and preserves the 2D-layered structure as long as 8 months in aqueous, meanwhile, the tensile strength of freestanding IL-MXene film is as high as 75.9 +/- 4.9 MPa and the increment is up to 84% when compared to that of untreated MXene film (41.2 +/- 4.5 MPa). A novel mechanism for improved chemical stability of MXene sheet was proposed and elucidated based on the radical-scavenging ability of IL and the surface chemistry of MXene sheet. This study provides a new strategy to achieve chemically stable Ti3C2Tx and improved mechanical strength of assembled MXene film, which is also available for other type of MXenes.

Automated summary

Ti3C2Tx MXene, with its superior metallic conductivity and excellent solution processability, faces challenges in practical applications due to its susceptibility to oxidation in humid or aqueous environments, resulting in the disassembly of the 2D-layered structure. By modifying Ti3C2Tx with imidazolium-based ionic liquid (IL), the chemical stability and mechanical strength of Ti3C2Tx can be significantly improved.