Integration of Mxene (Ti3C2Tx)-PVA-PAA Composite into Hanji: A Multifunctional Smart Fabric for Energy Harvesting, Thermoregulation, and EMI Shielding

Multifunctional smart fabrics have attracted a lot of attention due to the rapid downsizing of numerous electronic components and the emergence of wearable devices. One of the most advanced functions in such fabrics is energy harvesting in operating environments, while other multiple performances in terms of thermoregulation and electromagnetic interference (EMI) shielding would be desirable. Currently, heat, pressure, and triboelectricity are major energy sources that can be used with typical smart multifunctional materials. Herein, we report a novel smart fabric integrating energy harvesting using human perspiration and ambient moisture, as well as zonal heating for body temperature regulation and EMI shielding performances. In the smart fabric design, a blend of Mxene(Ti3C2Tx)-PVA-PAA is integrated into the environmentally friendly, traditional Korean paper, 'Hanji'. This composite exhibits high flexibility, oxidation resistance, hydrophilicity, and electrical conductivity. A precipitate of the mixture is obtained through ultrasonic treatment at room temperature, and then the asymmetric coating is applied to both sides of 'Hanji' using a vacuum filtration process. When the working fluid contacts the opposite side of the coated fabric, it rapidly penetrates through the coated interface of ‘Hanji’ and generates electricity through negatively charged nanofluidic channels. The introduction of hydrophilic polymer modulates the spacing of Mxene layers and prevents oxidation due to fluid exposure. The synergy between conductive Mxene and resistive hydrophilic polymer leads to achieving outstanding EMI shielding performance. Remarkably, even at low voltages, this composite shows efficient electricity-to-heat conversion and serves as a zonal heating element. The hydrophilic functional groups in the coating also provide humidity-sensing capabilities. The developed multipurpose smart fabric in this work will contribute to rationally designing multifunctional yet efficient energy harvesters using multiple sources.