Carbon materials and their composites for electromagnetic interference shielding effectiveness in X-band

Graphene and Fe2O3 filled composites for mitigation of electromagnetic pollution and protection of electronic appliances

Advances in waterborne polymer/carbon material composites for electromagnetic interference shielding

Recent progress in morphological engineering of carbon materials for electromagnetic interference shielding

Ti3C2Tx MXene/polyimide composites film with excellent mechanical properties and electromagnetic interference shielding properties

The exploration of flexible and lightweight electromagnetic interference (EMI) shielding materials with excellent shielding effectiveness, as a means to effectively alleviate electromagnetic pollution, is still a tremendous challenge. This paper proposes a conducting material named the textured Ni-encapsulated carbon tube, which can be applied in EMI shielding material by being inserted in the center of a poly(dimethysiloxane) (PDMS) polymer. We demonstrated that Pd2+ could be absorbed by the active groups on the plant fiber surface to catalyze the reduction of Ni2+ as a catalytic center by means of a textured Ni-encapsulated plant fiber. Owing to the outstanding heat-conducting capability of the Ni coating, the inner plant fiber was carbonized and attached to the Ni-tube inside the surface during annealing. To be precise, the textured Ni-encapsulated C tube was fabricated successfully after annealing at 300 °C. On further increasing the annealing temperature, the C tube disappeared gradually with the Ni coating being oxidized to NiO. Of note, the C tube acted as a support layer for the external Ni coating, providing sufficient mechanical strength. When combined with the coating PDMS layer, a flexible and lightweight EMI shielding material is fabricated successfully. It displays an outstanding EMI shielding effectiveness of 31.34 dB and a higher specific shielding efficiency of 27.5 dB·cm3/g, especially showing excellent mechanical property and flexibility with only 2 mm thickness. This study provides a new method to fabricate outstanding EMI shielding materials.

To cope with sophisticated application scenarios, carbon materials can provide opportunities for integrating multi-functionalities into superior electromagnetic interference (EMI) shielding properties. Nevertheless, carbon materials usually possess high electrical conductivity, which allows them to counteract electromagnetic waves by reflection. Moreover, the identification of factors that dominate the shielding mechanisms has typically been result-oriented, leading to a reliance on a trial-and-error approach for the development of shielding materials. Thus, it is crucial to identify the dominant factors for EMI shielding and elucidate the mechanism underlying the coordination of the balance between reflection and absorption in carbon materials. In this study, we developed a promising and viable approach to create Co@CNTs embedded in carbonized wood (CW) via chemical vapor deposition, producing Co@CNTs/CW foams. The CNTs, densely grown on the CW surface, tightly encapsulated the Co nanoparticles within them. By manipulating the Co content, the defect density and CNT length varied within the Co@CNTs. Through first-principles calculations, these variations substantially influenced the work function, charge density, and dipole moment of the Co@CNTs. Thus, defect-induced and interfacial polarizations were improved, inducing a transformation of the shielding mechanism from reflection to absorption. Regarding the Co@CNTs/CW foams, while high conductivity was essential for achieving satisfactory shielding performance, the enhanced polarization loss dominated the contribution of absorption to the overall shielding effectiveness. Taking advantage of the enhanced polarizations, the Co@CNTs/CW foams exhibited an impressive shielding effectiveness of 42.0 dB, along with an absorptivity of 0.64, which were instrumental in effectively minimizing secondary reflections. Remarkably, these as-prepared foams possessed outstanding hydrophobicity and Joule heating features with a water contact angle of 138° and a saturation temperature of 85.5 °C (2.5 V). Through the stimulation of voltage-driven Joule heating, the absorptivity of Co@CNTs/CW foams can be significantly enhanced to a range of 0.61 to 0.73, irrespective of the Co content. This research would provide a new avenue for designing carbon materials with an absorption-dominated mechanism integrated into EMI shielding performance.

Stretchable electromagnetic interference (EMI) shielding materials are now urgently required owing to recent advancements and wide applications of flexible electronic devices, which produced severe electromagnetic wave pollution, disturbing normal function of electronic devices and causing harmful responses on human body. However, recent studies on flexible EMI shielding materials failed on achieving high shielding effectiveness, large stretchability and excellent transparency. Herein, patterned EMI shielding meshes were fabricated by screen printing the thermoplastic polyurethane/silver micro-flakes (TPU/Ag) paste on a thin and flexible TPU substrate. The conductive composites were printed into various mesh patterns including square mesh shape, circle mesh shape, serpentine shape, etc. The EMI shielding meshes exhibit high stretchability of 80% before electrical insulation, high shielding effectiveness (SE) value of 45 dB for the square mesh shape. Therefore, the mesh patterned conductive composites with excellent EMI shielding performance, high flexibility and large stretchability are highly promising for applications in flexible and stretchable electronics.

The development of new electromagnetic interference (EMI) shielding materials with excellent overall performance has become a top priority, yet currently available EMI shielding materials are limited in terms of customization and application flexibility. A successful example is MXene-based EMI shielding materials, which exhibit outstanding electrical conductivity, tunable surface chemistry, and excellent solution processing, offering opportunities for intelligent customization in the field of EMI shielding. This review summarizes key developments from 2016 to 2024, highlighting MXene-based composites achieving EMI shielding effectiveness (SE) over 80dB, ultralow densities below 0.1g cm-3, and SSE/t values exceeding 30 000 dB·cm2 g-1. Herein, the latest advances in MXene-based EMI shielding materials, including fundamental experiments and intelligent customization, are outlined. Furthermore, recent progress in AI-assisted material design platforms, GHz-THz broadband shielding for 6G applications, and multifunctional integrated systems are highlighted. These efforts aim to provide efficient, lightweight, and flexible EMI shielding for next-generation electronic devices. Finally, based on the current research landscape, this article looks into the future development directions and application prospects of MXene-based EMI shielding materials, providing strategic insights for integration in advanced electronic systems.

Pickering emulsion strategy for high compressive carbon aerogel as lightweight electromagnetic interference shielding material and flexible pressure sensor

Facile construction of 2D MXene (Ti3C2Tx) based aerogels with effective fire-resistance and electromagnetic interference shielding performance

Electromagnetic shielding (ES) is an important aspect in selecting the material for designing of highly sensitive electronic devices controlled by radio frequency wave due to electromagnetic interference (EMI). Due to intense interaction of high frequency wave with the shielding material, the design of material with suitable impregnation of impurity influences the shielding mechanism. In the present investigation EMI shielding performance and electromagnetic absorption characteristics of epoxy blended graphene impregnated carbon fiber composite (EPCF@1%GN) has been intensively studied. The surface morphology of the sample EPCF@1%GN has been studied through Field emission scanning electron microscopy (FESEM) which provides the morphological facilitation to enhance the shielding effects of the fabricated material. The computation of shielding parameters indicates that the reference composite without graphene demonstrates the lowest total shielding effectiveness. In contrast, composites with graphene content exhibit significantly improved in EMI shielding performance about 20 dB for EPCF@1%GN, with nearly 70% more than for epoxy blended carbon fiber composite (EPCF) which may contributed due to enhanced absorption capability of the material designed. Additionally, the thermal tolerance has been analyzed through Thermo gravimetric analysis (TGA). Composites with graphene content displayed varying porosity characteristics, which may influence their electromagnetic properties highlighting shielding mechanism for microwave absorption. The significance of this study addresses the critical need for effective electromagnetic interference (EMI) shielding materials, particularly for applications in electronic devices, aerospace, and defense sectors. Traditional metal-based shielding materials, while effective, suffer from limitations such as weight and corrosion. This research explores a lightweight, polymer-based composite, offering a high-performance alternative with superior microwave absorption capabilities. The work highlights the transformation of EPCF@1%GN composite from reflection-dominated to absorption-driven shielding behaviour. The excellent thermal stability up to 625°C and enhanced dielectric losses, interfacial polarization, and improved impedance matching make this composite highly suitable for EMI shielding in advanced applications.

Owing to their remarkable lightweight, high specific surface area, and porous properties, carbon aerogels ascend to crucial candidates for multifunctional protection. Nevertheless, formidable challenges persist in carbon-based aerogels with a robust electromagnetic attenuation capacity, efficient thermal management, and infrared stealth simultaneously. In this study, a carbon aerogel, integrating electromagnetic attenuation and thermal management, is innovatively constructed using collagen fibers (CFs) extracted from leather waste with poly(vinyl alcohol) (PVA) via cyclic impregnation and high-temperature carbonization. This carbon aerogel is fabricated by hydrogen-bond-driven assembly of collagen fibers and polyvinyl alcohol, followed by high-temperature carbonization, and then loading of molybdenum disulfide-coated silver nanowires (AgNWs@MoS2) nanoparticles via cyclic impregnation. Notably, the CFs/AgNWs@MoS2 Carbon (CAMC) aerogel exhibits excellent electromagnetic interference shielding performance with an electromagnetic interference shielding effectiveness (EMI SE) of 72.1 dB and an electromagnetic reflectivity of approximately 0.27. It also demonstrates outstanding microwave absorption characteristics, including a minimum reflection loss (RLmin) of -48.77 dB at 12.16 GHz and an effective absorption bandwidth (EAB) of 4.01 GHz at a thickness of 2.8 mm. Additionally, the aerogel possesses superior heat retention and infrared stealth performance, maintaining a deep purple color close to the ambient background when exposed to 160 °C. It further exhibits efficient solar-to-thermal energy conversion and heat generation capability with a surface temperature reaching 79.1 °C under 250 mW/cm2 irradiation. Impressively, the CAMC carbon aerogel achieves near-ideal impedance matching with an impedance ratio (Z) of 1. This work not only solves the difficult problem of carbon aerogel's single property with poor protection performance but also achieves the sustainable recycling and utilization of leather waste, demonstrating profound application prospects in electromagnetic protection and thermal regulation.

Conventional metallic electromagnetic interference (EMI) shields, as well as the emerging 2D material-based shields, meet the shielding effectiveness (SE) needs of most applications. However, their shielding performance is dominated by the reflection of incoming radiation due to their high electrical conductivity, which leads to secondary pollution. This problem is getting exacerbated with the proliferation of electronics and communication networks in modern society. Thus, EMI shields that function dominantly by the absorption of incoming radiation are highly desirable. Such shields would be characterized by a green index, which is the ratio of absorbance over reflectance, close to or greater than one. For nonmagnetic materials, the best way to reduce the undesirable large impedance mismatch is to reduce the effective permittivity of the shield material. Here, we present a new EMI shield with a semiconductor Bi2S3 filler in a conducting PEDOT:PSS polymer matrix, instead of the conventional conductive fillers, to reduce the effective permittivity and demonstrate that even a light loading of only 10% Bi2S3 provides high SE of over 40 dB with a green index value of 0.75. Increasing the filler content to 15 wt% increases the green index close to unity while dropping the SE to 30 dB. The shielding mechanism is explained through electromagnetic parameter measurements and supplemented by density functional theory calculations. This work lays the foundation for the advancement of lightweight and ultrathin green EMI shields with minimum secondary pollution.

Double layered design for electromagnetic interference shielding with ultra-low reflection features: PDMS including carbon fibre on top and graphene on bottom

Electromagnetic interference (EMI) shielding materials with high efficiency and absorption-dominated performance are crucial for addressing the challenges posed by electromagnetic wave pollution in modern electronics. In this work, we developed a high-performance EMI shielding material by integrating functionalized CNTs (f-CNTs) into a dual gradient conductivity–porosity structure. The multilayer structure was fabricated using a facile hot-pressing method, enabling the combination of films with varying porosity and conductivity. This approach facilitates the scalable production of large-area shielding materials and allows for the customization of EMI shielding properties by adjusting the layer characteristics. The resulting composite exhibited outstanding EMI shielding effectiveness (SE) of up to 60.5 dB across the X-band frequency range, with an absorptivity of approximately 0.77. The porosity gradient effectively minimized impedance mismatch, enhancing absorption and internal scattering, while the conductivity gradient promoted the dissipation of residual EM waves through Ohmic loss and interfacial polarization. These synergistic effects contributed to the absorption-dominant shielding mechanism. This study introduces a design and fabrication strategy for high-performance EMI shielding materials, combining gradient porosity and conductivity to achieve superior absorption and shielding efficiency. The proposed method offers a scalable and versatile approach for tailoring electromagnetic shielding materials.