Bridging sheet size controls densification of MXene films for robust electromagnetic interference shielding

Numerous voids among the incompact layer-structure of MXene films result in their low ambient stability and poor innate conductivity for electromagnetic interference (EMI) shielding. Herein, we report a bridging-sheet-size-controlled densification process of MXene films by applying graphene oxide (GO) as a bridging agent. Specifically, the sheet size of GO is tailored to quantify a negative correlation of sheet size with densification for directing the preparation of most compact MXene-GO films. Benefiting from the shortest electron-transport -distance in the most compact structure, the conductivity of the MXene-GO film achieves 1.7 times (similar to 1.6 3 10(5) S/m) that of MXene film. The EMI shielding performance (similar to 5.2 3 10(6) dB/m) reaches the record-value among reported MXene films at 10 mm-scale thickness. Moreover, the compact structure boosts the ambient stability of MXene-GO films where the conductivity and EMI shielding performance remain 88.7% and 90.0% after 15 days, respectively. The findings rationale the structure-activity relationship of compact MXene films for flexible electronics.