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

Lightweight, thin electromagnetic interference (EMI) shielding film materials with high shielding effectiveness and good mechanical performance are highly required for flexible and portable electronics. Two-dimensional titanium carbide (Ti 3 C 2 T x MXene) has a great potential to meet these requirements because of the easy fabrication of ultrathin conductive films via solution processing. However, the production of strong pristine MXene films is still challenged by the presence of voids and wrinkles, as well as inferior flake alignment. In this work, high-performance pristine MXene films are produced by a spatially confined evaporation approach with controlled wet film thickness. When the cast dispersion layer is sufficiently thin, the skin effect is suppressed during evaporation, producing films with improved flake alignment and much fewer structural defects. As a result, the pristine MXene films deliver an ultrahigh tensile strength of 707 MPa and a high modulus of 66 GPa, together with a high electrical conductivity of 16600 S cm -1 . The high conductivity and intrinsic laminated structure endow the MXene films with superior EMI shielding performance in X-band (48.4 dB and 1.3 × 10 5 dB cm -2 g -1 for 1.0 μm thick films), being among the highest values reported.