Abstract:

Objective Currently, with the widespread application of electromagnetic technology, electromagnetic radiation pollution has become increasingly severe, creating a growing demand for lightweight, permeathable, and flexible electromagnetic interference (EMI) shielding materials. Two-dimensional transition-metal carbides/nitrides (MXenes) have been extensively employed in the fabrication of flexible EMI-shielding textiles by virtue of their exceptional EMI shielding properties. However, MXene-based fabrics prepared via the dip-coating method often exhibit unsatisfactory electrical conductivity and inadequate electromagnetic shielding performance, which limit their practical applicability. Therefore, improving the overall performance of MXene-based textiles through process optimization remains a critical challenge in current research.

Method Utilizing the inherent reducing capability of MXene, silver nitrate (AgNO₃) was in situ reduced to silver nanoparticles (AgNPs), which were anchored on MXene nanosheets to construct multilayered MXene/AgNPs heterostructures, significantly enhancing the electrical conductivity and electromagnetic interference shielding performance of MXene-based composites. While the conventional dip-coating method is a cumbersome and time-consuming process, this study proposes a layer-by-layer assembly strategy for constructing MXene/AgNPs heterostructures on cotton fabric and systematically investigates the influence of three key processing parameters in the dip-coating process on the electrical conductivity and electromagnetic shielding effectiveness of the composite fabric.

Results X-ray diffraction (XRD) analysis confirmed that the aluminum (Al) layer of the MXene precursor was completely removed and MXene exhibited a well-defined layered structure. The XRD pattern of MXene/AgNPs composites clearly show the characteristic peaks corresponding to the face-centered cube crystal structure of the silver nanoparticles. In addition, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analysis showed that AgNPs were distributed not only on the surface of MXene, but also between sheets of MXene. MXene/AgNPs composite cotton fabrics contain carbon, titanium, silver and other elements, which are evenly distributed on the surface of cotton fabrics, indicating that MXene/AgNPs conductive materials are successfully loaded on the cotton fabrics and form a continuous conductive network. The impedance matching coefficient of MXene/AgNPs is significantly higher than that of MXene, which makes the sheet resistance of MXene/AgNPs composite cotton fabric as low as 41.3 Ω/□, the total EMI shielding effectiveness reaches 27.6 dB, the absorption shielding effectiveness is 21.4 dB, 59.9% and 71.3% higher than that of pure MXene composite cotton fabric, respectively. Shielding effectiveness analysis reveals that the EMI shielding performance of MXene/AgNPs composite cotton fabric originates from the synergistic effect between MXene and AgNPs. Furthermore, the MXene/AgNPs composite fabrics prepared under various impregnation parameters exhibit significantly higher conductivity and EMI shielding performance than MXene composite cotton fabrics, which is attributed to the role of AgNPs as conductive bridges, effectively reducing interfacial resistance, enhancing interfacial polarization and dielectric losses, thereby improving electrical conductivity and electromagnetic wave absorption. Among the impregnation parameters, impregnation mass concentration has the most significant impact on conductivity, followed by impregnation cycles; impregnation time has little effect. In contrast, impregnation time most strongly influences EMI shielding, followed by impregnation, and impregnation mass concentration has the smallest effect. This fabric provides a feasible preparation strategy for flexible wearable shielding materials.

Conclusion MXene/AgNPs composite fabrics exhibit excellent electrical conductivity and EMI shielding properties, primarily by virtne of the synergy between MXene and AgNPs. AgNPs act as conductive bridges between MXene nanosheets, thereby reducing the impedance mismatch between MXene and significantly enhancing dielectric losses. At the same time, the multi-layer heterogeneous interface structure promotes multiple reflection and attenuation of electromagnetic waves, further improving the overall shielding effect. The study of parameter optimization of the impregnation process helps to precisely control the conductivity and EMI shielding properties of composite fabrics, saving material and time costs. This study provides a feasible preparation strategy for flexible wearable shielding materials.

Key words: MXene, silver nanoparticle, cotton fabric, conductive fabric, electromagnetic shielding, impregnation method