Robust Pristine MXene Films with Superhigh Electromagnetic Interference Shielding Effectiveness via Spatially Confined Evaporation

Lightweight,thin electromagnetic interference (EMI)shieldingfilm materials with high shielding effectiveness and good mechanicalperformance are highly required for flexible and portable electronics.Two-dimensional titanium carbide (Ti3C2T x MXene) has a great potential to meet theserequirements because of the easy fabrication of ultrathin conductivefilms via solution processing. However, the production of strong pristineMXene films is still challenged by the presence of voids and wrinkles,as well as inferior flake alignment. In this work, high-performancepristine MXene films are produced by a spatially confined evaporationapproach with controlled wet film thickness. When the cast dispersionlayer is sufficiently thin, the skin effect is suppressed during evaporation,producing films with improved flake alignment and much fewer structuraldefects. As a result, the pristine MXene films deliver an ultrahightensile strength of 707 MPa and a high modulus of 66 GPa, togetherwith a high electrical conductivity of 16600 S cm(-1). The high conductivity and intrinsic laminated structure endow theMXene films with superior EMI shielding performance in X-band (48.4dB and 1.3 x 10(5) dB cm(-2) g(-1) for 1.0 mu m thick films), being among the highest values reported.