# Electromagnetic Radiation Shielding Using Carbon Nanotube and Nanoparticle Composites
## 4 CNT-Based Materials for Electromagnetic Interference (EMI) Shielding
This study underscores the potential of multilayered films for various modern electronics applications, particularly in fields requiring flexible materials with superior EMI-shielding capabilities and thermal conductivity. [PERSON] and [PERSON] [64] discuss how the evolution of stretchable electronics has introduced new demands for flexible EMI-shielding materials. These materials need to be effective, lightweight, flexible, and stable to meet the needs of next-generation electronic devices. Among the materials used for EMI shielding, conductive polymer fabric composites (CPFCs) have gained attention due to their cost-effectiveness, light weight, ease of fabrication, high tensile strength, and dimensional stability. CPFCs are typically fabricated by depositing conductive fillers onto flexible polymer fabric. Polypropylene (PP) fabric, known for its recyclability and economic benefits, aligns well with the requirements of flexible polymer fabric due to its lightweight, and good tensile properties, and chemical resistance. Silver, with its exceptional electrical properties, mechanical robustness, and chemical stability, has emerged as a favored conductive filler for CPFCs. [PERSON] and [PERSON] highlight that integrating silver nanoparticles onto substrates like polyacrylonitrile (PAN) nanofibers via wet electroless deposition or onto cotton fibers via electroless deposition has yielded flexible and highly effective EMI-shielding materials. Nevertheless, inherent gaps between silver particles within a single layer can interrupt the continuity of the conductive network structure. To overcome this, high-conductivity nano-fillers such as CNTs and graphene (GP) are introduced to bridge the gaps and also to enhance conductivity. Thus, silver nanostructures/CNT composites are promising candidates for various applications due to their exceptional chemical activity, electrical conductivity, and EMI-shielding effectiveness. Furthermore, doping magnetic inorganic particles such as Fe\({}_{3}\)O\({}_{4}\), Co, and Ni will enhance the EMI SE and absorption properties of CPFCs. In situ precipitation and in situ polymerization methods have been used to fabricate magnetic conductive composites, but they often involve high manufacturing costs, complex chemical reactions, and structural modification and can reduce EMI-shielding performance. Hydrogen bonding is a simple, cost-effective, and environmentally friendly approach for addressing the challenges in preparing magnetic conductive materials. [PERSON] et al. [66] highlight the challenges posed by the inherent dielectric loss capability of carbon nanomaterials, including CNTs, in electromagnetic wave (EMW) absorption applications. These challenges include impedance matching imbalances and significant surface reflection, which can degrade EMW absorption performance. Additionally, effectively dispersing agglomerated CNTs remains a key hurdle in fully exploiting their potential for EMW absorption. To address these challenges, researchers have incorporated magnetic nanoparticles to enhance magnetic loss capability and improve the impedance matching of nanocarbon, thereby boosting EMW absorption performance. For example, an Ni/CNT composite created using a microwave welding method has achieved high EMW absorption with minimal reflection loss. Similarly, Co-Ni nanoparticles decorated with nitrogen-doped CNT arrays on ultrathin-reduced graphene oxide sheets have demonstrated good EMW-absorption capabilities. Another encouraging avenue involves using metal porphyrins and their derivatives as EMW-absorbing materials. Metal porphyrin supported by carbon materials provides active sites for EMW absorption, while the carbon materials ensure a high specific surface area and efficient mass transport. Porphyrin-functionalized CNTs show good capability for high EMW absorption due to their improved electrical contact and large heterogeneous interfaces. [PERSON] et al.