Robust liquid metal reinforced cellulose nanofiber/MXene composite film with Janus structure for electromagnetic interference shielding and electro-/photothermal conversion applications

MXene-based composite films are regarded as up-and-coming multifunctional electromagnetic interference (EMI) shielding materials. However, the conflict between strong mechanical properties and high electrical conductivity hinders their application in modern integrated electronics. Herein, in virtue of density-induced sedimentation, robust and multifunctional liquid metals-reinforced cellulose nanofibers (CNF)/MXene (LMs-CNF/MXene) composite films with Janus structure are fabricated by one-step vacuum-assisted filtration method. Not only does the nacre-like structure of the CNF/MXene layer not destroy, but the deposited liquid metals (LMs) layer can serve as conductive potentiation. Due to the special Janus structure, an “absorption-reflection-reabsorption” shielding process is created in LMs-CNF/MXene composite film to strengthen EMI shielding performance. Its shielding effectiveness can reach 51.9 dB at ∼27 µm, and the reflection coefficient falls to 0.89, below those of reported MXene-based shielding films. Meanwhile, the CNF/MXene layer can endow composite films with excellent mechanical properties with a super tensile strength of 110.3 MPa. Notably, the LMs-CNF/MXene EMI shielding composite films also integrate outstanding photo-/electrothermal conversion performances, which can effectively deice outdoors. The robust LMs-CNF/MXene EMI shielding composite films with satisfying photo-/electrothermal performances have extensive application prospects, such as aerospace, wearable electronics, and portable electronics.