Ultrathin, biomimetic multifunctional leaf-like silver nanowires/Ti3C2Tx MXene/cellulose nanofibrils nanocomposite film for high-performance electromagnetic interference shielding and thermal management

• Ultrathin, biomimetic Ag NWs/Ti 3 C 2 Tx/cellulose nanofibrils nanocomposites were prepared via a vacuum-assisted filtration. • Ti 3 C 2 Tx and Ag NWs formed leaf-vein conductive frameworks that endowed the composites superior electrical conductivity. • High electromagnetic shielding effect lies in the enhanced ohmic losses and interfacial polarization in the composites. • Joule heater behaved fast response, temperature aging stability and high-precision tunability under low voltage supply. Herein, we reported an ultrathin, flexible and super conductive silver nanowires (Ag NWs) doped Ti 3 C 2 Tx/Cellulose nanofibrils (CNFs) films by constructing biomimetic leaf-vein scaffolds via a facile vacuum-assisted filtration. Leaf-vein structure was built by Ti 3 C 2 Tx nanosheets and Ag NWs, offering numerous junctions and forming 3D conductive skeletons. The Ag NWs doped Ti 3 C 2 Tx/CNFs film with 85 wt% Ti 3 C 2 Tx and 5 wt% Ag NWs exhibited extremely high electrical conductivity and superior electromagnetic interference shielding effectiveness (EMI SE) value with a small thickness of 6 µm in X-bands (8.2–12.4 GHz). Synergetic effect on the mechanical property was observed for film with 70 wt% Ti 3 C 2 Tx and 10 wt% Ag NWs, exhibiting EMI SSE/t of 19,613.5 dB cm 2 g −1 , much higher than Ti 3 C 2 Tx/CNFs film. The electron migrating and hopping in the leaf-like conductive networks would lead to the massive ohmic and dielectric losses on the dipole-rich surface of Ti 3 C 2 Tx nanosheets. Additionally, the proof-of-concept of the proven film used as a Joule heater for thermal management was ascertained, which possessed fast response, aging stability, high-precision and ultralow voltage supply (1–3 V). Due to those preferential characteristics, the biomimetic Ag NWs doped Ti 3 C 2 Tx/CNFs materials can be integrated into the emerging applications, such as intelligent garments, thermotherapy and wearable devices.