Self-Assembling Ultrathin MXene/Cellulose Nanofiber/MXene Composite Film for High-Performance Electromagnetic Interference Shielding

Ti3C2T x MXene films exhibited good electromagnetic interference (EMI) shielding performance. However, the poor mechanical property and durability of Ti3C2T x MXene films limited their commercial application. Herein, the ultrathin flexible conductive MXene/cellulose nanofiber (CNF)/MXene composite films with "sandwich" structure were successfully prepared by simple vacuum-assisted filtration process. The addition of CNF can shield more electromagnetic microwaves (EMWs) via multiple reflections in the inner space and enhance the mechanical property of composite films by effectively welding the loosely MXene together. The composite film exhibited excellent EMI shielding effectiveness (up to 54.68 dB) at an ultrathin thickness (about 76 μm) as well as high electrical conductivity (up to 1610.51 S/m), which was mainly attributed to the hierarchical lamellar "sandwich" structure, where CNF was bonded to Ti3C2T x MXene. The prepared flexible conductive composite films with brilliant EMI shielding effectiveness and good mechanical property possessed promising potential in various fields such as electromagnetic wave protection, weaponry and wearable electronics.