High wet-strength MXene/lignin-containing cellulose nanofibrils composite films with Janus structure for electromagnetic shielding and Joule heating.

Developing MXene-based electromagnetic interference (EMI) shielding composite films with exceptional wet mechanical properties is crucial to address the limitation of conventional MXene-based EMI shielding composite films in humid environments. Herein, we present a fabrication strategy for Janus-structured MXene-based EMI shielding composite films with exceptional wet mechanical and Joule heating performances. Through depositing tannic acid-modified MXene (TM) on maleic anhydride-modified lignin-containing cellulose nanofibril (MLCNF) film using a scalable vacuum filtration and hot-pressing strategy. The Janus-structured MLCNF/TM composite film (J-MLCNF/TM) was fabricated. With the synergistic contribution of the introduced Janus structure, TM, and MLCNF substrate with high wet mechanical properties and extensive hydrogen bonding interactions, J-MLCNF/TM achieved an optimal balance between mechanical and EMI shielding properties. The optimized J-MLCNF-50 %/TM (50 wt% MLCNF) exhibits excellent wet tensile strength (72.69 MPa), remarkable wet toughness (15.43 MJ m), and high EMI shielding efficiency of 36.22 dB. Furthermore, J-MLCNF-50 %/TM showed outstanding Joule heating performance at low voltages, featuring excellent heating stability, deicing capability, and reliable performance in humid environments. In summary, this study offers a facile and efficient approach for the application of MXene-based EMI shielding materials in humid environments.