Ultrathin Ti3C2Tx MXene/Cellulose nanofiber composite film for enhanced mechanics & EMI shielding via freeze-thaw intercalation

Developing high-performance and cost-effective microwave-absorbing materials for large-scale production is crucial in addressing the current electromagnetic pollution problem. This has become a focus of scientific research. This study proposes a cost-effective freeze-thaw method to enable large-scale production of MXene-based flexible films. This method streamlines the preparation process and produces ultrathin flexible MXene/CNF composite films with a multidimensional layered structure. The multidimensional layered structure provides additional scattering and reflecting paths for electromagnetic waves, increasing the interaction time between electromagnetic waves and the material. Additionally, the redistributed interfacial charge enhances the dielectric loss and electromagnetic shielding performance for the shielding material, thereby improving microwave absorption efficiency. Owing to these advantages, the MXene/CNF composite films prepared using the freeze-thaw method exhibit excellent electromagnetic shielding and mechanical properties. The conductivity of the composite film can reach 165.9 S cm⁻¹ with a shielding effectiveness of 54.7 dB, and a high efficiency of 99.74 %. According to the simulations using a finite element method (FEM), the arrangement and rotation angles of all CNF layers significantly affect the electromagnetic shielding effectiveness of the MXenen/CNF composite films.