Flexible and ultrathin MXene/nanofiber composite films by self-stacking assembly for enhanced electromagnetic interference shielding performance

With the huge demand and rapid development of portable, intelligent, and microscale equipment, more stringent requirements are put forward for the thickness, performance, and cost of the electromagnetic interference (EMI) shielding materials. In this work, flexible and ultrathin MXene/nanofiber (MX/NF) composite films with excellent EMI shielding performance are designed and fabricated by self-stacked assembly through vacuum-assisted filtration. 2D MXene nanosheets are utilized as conductive materials to construct a conductive path, and cellulose nanofibers (CENF) and carbon nanofibers (CANF) are applied to improve the flexibility and supportability of the designed composite films. When the mass ratio of MXene to CANF-CENF is 4:1 and the thickness of the composite film is 11 μm, the shielding effectiveness (SE) of the EMI film reaches 43.1 dB. In addition, the ranking efficiency product (REP) sustainability analysis is performed for the MX/NF-0.8 and three other EMI films, and it is found that the MX/NF-0.8 composite film possesses the largest REP value of 0.787. Besides, it exhibits the advantages in terms of degradability and shielding performance. The presented flexible, ultrathin EMI shielding films with layer-stacked structure reveal great application potential in the field of EMI shielding and could be appliable for wearable intelligent devices.