Lab Electrospinning System| Constructing multilevel nanostructures fiber composites for NIR/UV/X-raymultiband electromagnetic protection

Professor Wang Ce of Jilin University & Professor Liu Yong of Beijing University of Chemical Technology: Hierarchical Nanostructured Fiber Composites for Multi-band Electromagnetic Protection Covering NIR/UV/X-ray

With the rapid development of science and technology, electromagnetic interference has drawn widespread attention in critical fields such as medical care, high-end electronic devices, and aerospace. Electromagnetic waves (EMW) may interfere with human health, precision instruments, and communication systems. Such interference can manifest as either single-band or complex multi-band radiation environments. However, most existing shielding materials are designed for specific frequency bands, making them inadequate for multi-band electromagnetic protection. The development of efficient multi-band electromagnetic protection materials that combine lightweight and flexible properties has become a significant challenge in materials science.

Recently, Professor Wang Ce from Jilin University and Professor Liu Yong's team from Beijing University of Chemical Technology published their latest research findings titled "Constructing Multilevel Nanostructures Fiber Composites for NIR/UV/X-ray Multiband Electromagnetic Protection" in the journal Carbon. The researchers prepared Bi/WO₃/MWCNTs/PAN fiber composites with hierarchical nanostructures through electrospinning and post-processing techniques. By utilizing the strong absorption capacity of multi-walled carbon nanotubes (MWCNTs) for low-frequency electromagnetic waves, the high photoelectric effect of high atomic number (Z) materials Bi and WO₃, and the porous structure of nanofibers, excellent multi-band electromagnetic shielding performance was achieved.The resulting Bi/WO₃/MWCNTs/PAN fiber composites could block 99.6% of near-infrared radiation and 99.95% of ultraviolet radiation at a thickness of 0.12 mm. At 1.92 mm thickness and 33 keV X-ray photon energy, they provided 55.2% X-ray attenuation and a mass attenuation coefficient of 13.94 cm² g⁻¹. Additionally, Bi/WO₃/MWCNTs/PAN composites feature lightweight, flexibility, good thermal insulation, heat resistance, and electrical insulation, meeting broader practical application needs and showing potential in electromagnetic protection for medical and other critical fields.

Fig. 1: Preparation process and characterization of Bi/WO₃/MWCNTs/PAN fiber composites

The Bi/WO₃/MWCNTs/PAN fiber composites were prepared through electrospinning combined with two post-processing techniques. First, MWCNTs and WO₃ nanorods were uniformly embedded in PAN nanofibers via electrospinning. Subsequently, during solvothermal reaction, WO₃ nanorods served as seeds to induce in-situ growth of WO₃ nanoparticle layers on PAN nanofiber surfaces. The presence of WO₃ nanorods not only promoted uniform deposition of WO₃ nanoparticles but also effectively regulated crystal growth behavior on fiber surfaces, forming stable WO₃ phases and achieving precise control of material microstructure. Finally, using successive ionic layer adsorption and reaction (SILAR) method, metallic Bi nanowires were further grown on WO₃ nanoparticle layers, constructing Bi/WO₃/MWCNTs/PAN fiber composites with hierarchical nanostructures.

Fig. 2: Near-infrared shielding performance and thermal insulation properties of Bi/WO₃/MWCNTs/PAN fiber composites

The Bi/WO₃/MWCNTs/PAN composite nanofiber membranes exhibited excellent near-infrared shielding and thermal protection performance. Transmission spectroscopy showed only 0.4% near-infrared transmittance at 2500 nm. Infrared thermal imaging verified its good thermal insulation effect: on a 36.5°C heating stage, the membrane surface temperature only rose to 29.1°C, just 4.8°C above ambient temperature. Furthermore, the composite's low thermal conductivity (36.96 mW m⁻¹ K⁻¹) originated from heat conduction suppression by the porous structure, effectively isolating external heat. TGA tests showed a heat resistance temperature up to 289.8°C, demonstrating excellent thermal stability and protective capability.

Fig. 3: UV shielding performance of Bi/WO₃/MWCNTs/PAN fiber composites

The Bi/WO₃/MWCNTs/PAN fiber composites demonstrated outstanding UV shielding performance. Tests revealed UVA and UVB transmittance of only 0.05%, with a UPF value as high as 2000, far superior to traditional materials. UV-Vis spectra indicated that MWCNTs' absorption and scattering significantly reduced UV transmittance, while Bi and WO₃ further enhanced UV absorption. Moreover, the material maintained stable shielding performance under high-intensity UV radiation.

Fig. 4: X-ray shielding performance and mechanism analysis of Bi/WO₃/MWCNTs/PAN fiber composites

At 33 keV energy, the Bi/WO₃/MWCNTs/PAN fiber composites achieved a mass attenuation coefficient of 13.94 cm² g⁻¹ and 55.2% attenuation rate, maintaining 15.1% shielding effectiveness even at 100 keV high energy, with performance approaching or surpassing lead glass. This excellent performance originates from the high atomic number absorption characteristics of Bi and WO₃, combined with the conductive network constructed by MWCNTs and porous nanostructure, enabling multiple photon scattering and energy dissipation, significantly reducing secondary radiation from Compton scattering. Simulation and comparison results further verified its outstanding protective effects, demonstrating great potential as lightweight, high-efficiency electromagnetic protection material.

Paper link: https://authors.elsevier.com/a/1k-Bb1zUAddMT