Abstract:

Objective The two-dimensional material MXene can be easily integrated with textiles because of its excellent dispersion, good mechanical properties, and high conductivity, and has shown potential applications in many areas. In order to expand the application of two-dimensional titanium carbide materials into smart textiles, Ti₃C₂T_x and carbon nanotubes (CNTs) were sprayed on pure nonwovens as the substrate to prepare a multifunctional electronic textile which integrates sensing, energy storage, and thermal energy conversion.

Method Ti₃C₂T_x MXene sheets were synthesized through the typical chemical etching method by selectively etching Al layer from Ti₃AlC₂ phase. Ti₃C₂T_x (2 mg/mL) and CNTs dispersion (2 mg/mL) were then ultrasonically mixed (at a volume ratio of 1∶1) and repeatedly sprayed on nonwoven fabric substrate until the surface resistance of the fabric was lower than 150 Ω. The Ti₃C₂T_x/CNTs/nonwoven (MCF) composite was finally prepared and characterized by scanning electron microscope and X-ray diffraction. In addition, the photothermal and electrothermal conversion performance, electrochemical properties and sensing performance were also explored.

Results The thread-like CNTs on the fabric surface were wrapped around the entangled Ti₃C₂T_x flake, connecting Ti₃C₂T_x from different regions and forming a stable conductive network. The Ti₃C₂T_x was successfully synthesized and uniformly attached on the surface of nonwoven substrate. When MCF was used for photothermal conversion, it was quickly heated up to 65 ℃ in 60 min and maintained stable. In terms of the electrical heating performance, the thermal response time of MCF was shorter than 2 s, and the aperture on the infrared thermal image was uniformly distributed. The reason is that the addition of CNTs further improved the overall conductivity of the material, and exploited the large volume and contact area of the CNTs to bond with more Ti₃C₂T_x, and created more conductive pathways on the surface of the fabric. When the MCF electrode was used in a flexible semi-solid supercapacitor, the specific capacitance remained at 70 mF/cm² even at a high current density of 2 A/cm². After 10 000 cycles, the MCF still maintained a capacitance retention of 74%, indicating that the MCF electrode had a good cycling durability. In addition, the MCF was also used as sensors and fixed on the neck, wrist, fingertips, knee, and elbow of the human body to monitor human motions. With each bending of the human body, the resistances of MCF underwent regular changes, which were captured and recorded clearly and stably.

Conclusion MCF was successfully prepared by modified mixed solution of CNTs/Ti₃C₂T_x on the nonwoven substrate using a simple spraying method. Owing to the synergistic effect of CNTs and MXene films, MCF was rapidly heated up to 65 ℃ at room temperature of 32 ℃ after being exposed to sunlight and 115 ℃ under a voltage of 15 V, demonstrating good photothermal conversion and joule thermal performance. When used as a flexible semi-solid supercapacitor electrode, MCF exhibited a high specific capacitance of 125 mF/cm². Additionally, MCF could be applied as a flexible strain sensor to detect human motions, exhibiting significant negative resistance changes and high sensitivity. In summary, MCF presents great potential applications in wearable electronic products and multifunctional garments.

Key words: conductive fabric, Ti₃C₂T_x, carbon nanotube, photothermal performance, electric heating performance, capacitor, sensor, cellulose nonwoven fabric