Flexible multifunctional MXene@Ag nanowires/cotton fabric inspired by transport of nutrients by roots for electromagnetic shielding, infrared stealth, Joule/solar heating and flame retardancy

Abstract

With the rapid development of 5G communication technology and intelligent detection technology, electromagnetic shielding/infrared stealth fabrics with Joule/solar heating performance can meet the needs of wearable electronic devices for multi-application scenarios. Two-dimensional (2D) transition metal carbides and nitrides (MXenes) are ideal candidates for constructing efficient conductive networks in EMI SE fabrics due to their layered structure and high conductivity. However, it is difficult for MXene nanosheets to assemble into excellent interconnected conductive networks due to the irregular size and stacking of MXene sheets after MXene etching. Inspired by transport of nutrients by roots, a three-dimensional (3D) efficient conductive network was constructed by bridging one-dimensional (1D) Ag nanowires (AgNWs) into the highly conductive 2D MXenes, and a series of flexible multifunctional MXene@AgNW/cotton fabrics with excellent EMI SE performance was obtained. The average EMI SE value of MXene@AgNW/cotton fabrics can reach 70.6 dB in the X band. The oxidation resistance of the fabric is enhanced after spraying perfluorooctyltriethoxysilane (PFOTES) on the surface, and the surface water contact angle reaches 135.1°, providing excellent self-cleaning performance. MXene@AgNW/cotton fabric exhibits an average infrared emissivity of 0.25 (3–5 μm) and 0.17 (8–14 μm), showing excellent camouflage capability for infrared thermal signals under an infrared camera, generating a temperature difference of about 132.2 °C with a hot stage at 200 °C. MXene@AgNW/cotton fabric shows good electrical heating performance under low voltage loading (temperature reaches 150 °C at 3.5 V) and it also exhibits photothermal properties, showing a temperature of 120 °C under light density irradiation of 1900 W m⁻² within 180 s, which can realize the functions of hot compress therapy and cold preservation. The limiting oxygen index (LOI) value of MXene@AgNW/cotton fabric is 27.5%, which proves that MXene@AgNW/cotton fabric exhibits fire safety in practical applications. This work provides a paradigm for the construction of flexible multifunctional EMI SE fabrics.