Electromagnetic Wave Shielding Research Articles

Broadband electromagnetic wave absorption properties of RGO cement-based composite

In this study, a cement-based composite was prepared using reduced graphene oxide (RGO) as a raw material via an ethanol liquid-phase mixing pre-dispersion process. The microstructure of cement-based composites with varying RGO contents was discussed, and a systematic investigation was conducted into the electromagnetic wave absorption (EWA) performance of RGO-cement composites within the frequency range of 2–18 GHz. The results indicate that the RGO content significantly impacts its wave absorption performance. Notably, at an RGO content of 3.0 wt%, the wave absorption performance experiences substantial enhancement. For instance, the minimum reflection loss (RLmin) of −48.33 dB at 8.9 GHz with a coating thickness of 2.6 mm is achieved, while an effective absorption bandwidth (EAB) of 5.02 GHz is attained with a thickness of only 1.6 mm, covering nearly the entire Ku-band. The incorporation of high specific surface area RGO into cement materials results in abundant interface polarization losses and additional electromagnetic wave transmission paths, effectively boosting the EWA performance. Consequently, these materials exhibit significant potential for applications in the field of electromagnetic wave shielding.

Exploring a novel approach for the synthesis of MIL-53(Fe)/reduced graphene oxide composites with preserved structural integrity for high performance for electromagnetic wave shielding

Efficient electromagnetic waves absorbing materials while preserving structural integrity based on MIL-53(Fe)/reduced graphene oxide composites remains a challenging task. Most reported preparation techniques compromise structural integrity which limits its practical applications. This study reports innovative method by carefully controlling pyrolysis in a tubular furnace to produce Pyrolyzed MIL-53(Fe)/reduced graphene oxide (P-MIL-53(Fe)/RGO) composites to safeguard structural integrity while preserving RGO’s structure and achieving high EMI shielding efficiency. Various mass ratios of reduced graphene oxide were investigated (15%, 20%, and 30%) to indicate the impact of calcination in changing the degree of graphitization and its effect on the shielding performance. P-MIL-53(Fe)/RGO30 stands out, achieving notable total shielding effectiveness (SET) of 46.5 dB and absorption shielding efficiency (SEA) of 40.3 dB with 2 g of reduced graphene oxide (5 mm thick). The study offers a simple strategy to produce the desired composite with preserved reduced graphene oxide’s structural integrity which has a potential EMI shielding performance. These insights hold promise for diverse applications demanding robust, high-performance electromagnetic wave shielding materials.

Fabrication of innovative multifunctional dye using MXene nanosheets.

The increasing demand for natural and safer alternatives to traditional hair dyes has led to the investigation of nanomaterials as potential candidates for hair coloring applications. MXene nanosheets have emerged as a promising alternative in this context due to their unique optical and electronic properties. In this study, we aimed to evaluate the potential of Ti3C2Tx (Tx = -O, -OH, -F, etc.) MXene nanosheets as a hair dye. MXene nanosheet-based dyes have been demonstrated to exhibit not only coloring capabilities but also additional properties such as antistatic properties, heat dissipation, and electromagnetic wave shielding. Additionally, surface modification of MXene using collagen reduces the surface roughness of hair and upregulates keratinocyte markers KRT5 and KRT14, demonstrating the potential for tuning its physicochemical and biological properties. This conceptual advancement highlights the potential of MXene nanosheets to go beyond simple cosmetic improvements and provide improved comfort and safety by preventing the presence of hazardous ingredients and solvents while providing versatility.

Expediting High‐Yield Mxene Carbides and Nitrides Synthesis for Next‐Generation 2D Materials

AbstractThis research aims to enhance MXene (Ti3C2Tx) synthesis from MAX phases (Ti3AlC2) through a hydro‐solvothermal exfoliation process, with a focus on reducing time and temperature requirements. Prior hydrothermal studies have encountered challenges due to high reaction temperatures. In comparison to previous research, this work achieves superior results at lower temperatures. Two optimized MXene preparation routes are investigated and the etchant's impact on MXene surface chemistry is analyzed. Comprehensive X‐ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray Spectroscopy (EDS), X‐ray Photoelectron Spectroscopy (XPS), Fourier transform infrared (FTIR), Raman spectroscopy, and Atomic Force Microscopy (AFM) analyses provide insights into hydrosolvothermal synthesis (H‐Ti3C2Tx ) multilayers(ML), confirming/challenging recent spectroscopic assignments. Remarkably, hydro‐solvothermal treatment induces significant changes in surface composition, increasing hydroxyl (─OH) groups without oxidation and reducing fluorine (─F) groups on the H‐ Ti3C2Tx surface. These study's results hold promise for applications in energy storage and electromagnetic wave shielding. This research accomplishes three main objectives: i) secures hydrothermal synthesis of two‐ dimensional (2D) MXenes, ii) efficiently utilizes lithium fluroide‐ hydrochloric acid (LiF−HCl) etching for high‐quality MXene flakes with minimal defects, and iii) understands hydro‐solvothermal kinetics. This approach advances MXene synthesis with enhanced material quality and production efficiency (>98%), in a more eco‐friendly and safer manner. This eco‐conscious synthesis underscores MXene's versatility and eco‐friendly methods' significance, reshaping MXene exploration and sustainable material synthesis, with potential implications for future electrochemical applications.

Electromagnetic interference shielding performance of lanthanum ferrite with MWCNT and graphene in the polyethylene polymer matrix in X-band frequency

In the present study, a combination of Lanthanum ferrite (LaFeO3) magnetic nanoparticles with multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP) was prepared and used as conducting filler. As prepared Nanofillers were incorporated with the Low-density polyethylene (LDPE) with the melt blending process. The polymer composite was used to study the electromagnetic interference (EMI) shielding behaviour from 8.2 to 12.4 GHz. The electromagnetic (EM) wave shielding was ascribed to the dielectric and magnetic loss phenomena by incorporating graphene, MWCNT, and LaFeO3. The maximum shielding effectiveness of 33.57 dB was obtained with the critical concentration of 50:5:40:5 wt% sample.

Magnetic Liquid Metals: A Review

AbstractMagnetic liquid metal (MLM) is a mixture of magnetic particles with gallium‐based liquid metals which utilizes an unconventional combination of fluidity, high thermal/electrical conductivity, biocompatibility, and magnetism. Recently, from materials to applications, studies on MLMs have drastically increased. Single or multiple MLMs can be precisely positioned or can act as a carrier for handling other objects. MLMs are also used in biomedical applications such as cancer treatment by hyperthermia and precision delivery of cancer drugs on tumors, or antibacterial coating which kills bacteria. In electronics applications, MLMs are used for magnetic field‐driven patterning of metallic lines, reconfigurable interconnects, electronic tattoos, and reconfigurable electromagnetic wave shielding. Phase change (solid/liquid) of MLMs adds another unique capability, morphing. A combination of innovations in the micro/nano robots and MLMs has huge potential to bring an unprecedented disruptive technology for a wide variety of applications including self‐morphing shape‐recovery robots, highly localized cancer treatment, and reconfigurable stealth/camouflage, among others. This article comprehensively reviews recent developments in MLMs from the materials to methods of preparation, locomotion of MLMs, their applications, and future outlooks.

Flexible and efficient MXene/PANI/aramid fabrics with high interface durability for wearable electromagnetic wave shielding

The electromagnetic pollution of electronic equipment has a negative impact on the health of aircrews working in special environments. Yet wearable electromagnetic interference (EMI) shielding materials capable of versatility still a challenge. Herein, an effective strategy is developed to construct MXene/PANI/aramid fabric by growing vertically aligned polyaniline (PANI) nanowire arrays on the aramid fabric through impregnating with highly conductive MXene nanosheets to avoid the new accumulation/aggregation of MXene followed by simple polyetherimide (PEI) dipping packaging. In-situ polymerization of PANI solved the problem of weak interaction between inert aramid fiber and MXene to some extent, while PEI packaging solves the existing problem of easy-to-fall MXene nanosheets. The final prepared single-layer composite fabric has suitable highest EMI shielding efficiency value of 31.87 dB, good washing resistance and excellent bending stability (only 4% of the conductivity decreases after 1000 bends). This study provides a simple and easy large-scale method to fabricate multifunctional wearable fabrics to meet the practical application in EMI shielding area.

Multifunctional elastomeric composites based on 3D graphene porous materials

Abstract3D graphene porous materials (3GPM), which have low density, large porosity, excellent compressibility, high conductivity, hold huge promise for a wide range of applications. Nevertheless, most 3GPM have brittle and weak network structures, which limits their widespread use. Therefore, the preparation of a robust and elastic graphene porous network is critical for the functionalization of 3GPM. Herein, the recent research of 3GPM with excellent mechanical properties are summarized and the focus is on the effect factors that affect the mechanical properties of 3GPM. Moreover, the applications of elastic 3GPM in various fields, such as adsorption, energy storage, solar steam generation, sensors, flexible electronics, and electromagnetic wave shielding are comprehensively reviewed. At last, the new challenges and perspective for fabrication and functionalization of robust and elastic 3GPM are outlined. It is expected that the perspective will inspire more new ideas in preparation and functionalization of 3GPM.

Ultra-broadband composite terahertz absorber prediction based on K-nearest neighbor

Broadband Terahertz (THz) absorbers with characteristics of thin thickness, wide absorption bandwidth, and tunability can play a significant role in the field of electromagnetic (EM) wave shielding. However, when designing absorbers, it is necessary to analyze a large number of variable structural parameters to obtain the desired broadband absorption spectrum. Therefore, it is difficult to obtain the optimal structure efficiently and accurately by artificially designing the broadband absorbers because a large amount of structural parameter optimization work is required. This study uses the K-nearest neighbor (KNN) algorithm to predict the design of composite multilayer terahertz absorber. The prediction obtained an ultra-large effective absorption bandwidth of 5.493 THz, with an absolute percentage error (APE) of only 0.69%. In addition, the proposed absorber has functions such as polarization insensitivity, stable performance for large incident angles, and absorption intensity tunability. This study will provide a new approach for the structure design of ultra-broadband terahertz absorbers in the future.

The Contribution of the Pore Size of Titanium DC (Direct Current) Sputtered Condensation Polymer Materials to Electromagnetic Interruption and Thermal Properties

Using special materials has been in the spotlight, along with their multifunctional demands, research on electromagnetic interruption, thermal characteristics, biosignal sensors, secondary batteries, etc. In this study, titanium was sputtered into a condensation polymer material and considered in depth in terms of electromagnetic interruption, thermal properties, infrared blocking, etc. As a result of observing the electromagnetic wave shielding effect, the electromagnetic wavelength value decreased from 168.0 to 42.7 to 64.0 when titanium DC sputtered film samples were placed in front of the electromagnetic wave source. The titanium DC sputtered samples significantly reduced electrical resistance compared to the untreated samples. In addition, the IR transmittances of the titanium sputtered specimens were decreased compared to the untreated specimens. When only the cross-section was treated with titanium sputtering and the titanium surface was directed toward the infrared irradiator, the infrared permeability was 64.3 to 0.0%. After taking an infrared thermal image, ΔH, ΔV, ΔS, ΔY, ΔCr, and ΔCb values were calculated. It is believed that the titanium DC sputtered polyamide materials produced in this study can be used for high-functional protective clothing, sensors by applying electromagnetic interruption, IR blocking, and stealth functions.

High-Performance, Multifunctional, and Designable Carbon Fiber Felt Skeleton Epoxy Resin Composites EP/CF-(CNT/AgBNs)x for Thermal Conductivity and Electromagnetic Interference Shielding.

In this work, high-performance epoxy resin (EP) composites with simultaneous excellent thermal conductivity (TC) and outstanding electromagnetic shielding properties are fabricated through the structural synergy of 1D carbon nanotubes and 2D silver-modified boron nitride nanoplates (CNT/AgBNs) to erect microscopic 3D networks on long-range carbon fiber (CF) felt skeletons. The line-plane combination of CNT/AgBNs improve the interfacical bonding involving EP and CF felts and alleviate the phonon scattering at the interface. Eventually, the TC of the EP composites is enhanced by 333% (up to 0.91W m-1 K-1 ) with respect to EP due to the efficient and orderly transmission of phonons along the 3D pathway. Meanwhile, the unique anisotropic structure of CF felt and exceptional insulating BNs diminishes the electronic conduction between CNT and CFs, which protects the through-plane insulating properties of EPcomposites. Furthermore, the EPcomposites present favorable electromagnetic shielding properties (51.36dB) attributed to the multiple reflection and adsorption promoted by the multiple interfaces of stacked AgBNs and heterointerface among CNT/AgBNs, CF felt and EP. Given these distinguishing features, the high-performance EP composites open a convenient avenue for electromagnetic wave (EMW) shielding and thermal management applications.

Highly anisotropic MXene@Wood composites for tunable electromagnetic interference shielding

Smart electromagnetic interference (EMI) shielding material with a dynamically adjustable electromagnetic response based on real-time requirements is attractive for future electromagnetic devices. Herein, a highly anisotropic [email protected] composite ([email protected]) with convenient shielding effectiveness (SE) regulation is fabricated by coating MXene on the natural wood surface. Benefiting from the anisotropic pore structure and abundant free radicals, the [email protected] displays a better impedance match in the tangential-section than in the cross-section. In the tangential-section, [email protected] can respond to changes in the dihedral angle between the wood grain and the electromagnetic wave electric field, and achieve the off/on switch between electromagnetic wave transmission and shielding. The SE ranges from 27.4 to 57.6 dB as the dihedral angle alters from 90° (perpendicular) to 0° (parallel). The finite element analysis simulation further reveals the tunable electromagnetic response. This sustainable EMI shielding material based on natural wood offers a novel platform for exploiting intelligent electromagnetic devices.

Wood biomass-derived carbon for high-performance electromagnetic wave absorbing and shielding

With the speedy advancement of wireless communications, electromagnetic wave (EMW) pollution and electromagnetic interference (EMI) are gradually austere, which makes it an urgent need to develop high-performance EMW absorbers and shields. Carbon-based materials are important members of the family of EMW absorbing and shielding materials, due to their satisfactory electrical conductivity, low density, and good corrosion resistance. Especially, wood biomass-derived carbon materials, including carbonized cellulose, lignin and wood monolith, are acclaimed for their rich conductive network, unique porous structure, and effective loading of functional fillers, which promotes high-efficiency EMW absorption and shielding, and provides a new idea for using wood biomass resources in a high-value way. Additionally, due to the high yield of wood biomass, the mass production of carbonized wood biomass-derived EMW absorbers and EMI shields becomes more promising compared with other carbon materials. Hence, relevant studies should be summarized. Meanwhile, the functions of carbon materials need to be clarified and the importance of carbon materials needs to be highlighted. In this review, the roles of wood biomass-derived carbon in various EMW absorbing and shielding materials were emphasized, along with an analysis of related studies. Meanwhile, the main obstacles and the prospects of wood biomass-derived carbon were proposed.

Mechanical and Electrical Properties and Electromagnetic-Wave-Shielding Effectiveness of Graphene-Nanoplatelet-Reinforced Acrylonitrile Butadiene Styrene Nanocomposites

Polymer nanocomposites have attracted global attention as a metal replacement for electrical and electronic applications. Graphene nanoplatelets (GNPs) are widely used as a nanoreinforcement to enhance the functional and structural properties of thermoset and thermoplastic polymers. In the present study, ABS nanocomposites were prepared by reinforcing 3–15 wt.% GNPs in steps of 3 wt.%. The neat ABS and ABS+GNP nanocomposite specimens for the mechanical test were prepared using injection molding, followed by extrusion, as per American Society for Testing and Materials (ASTM) standards. It was found that the modulus of ABS improved due to the reinforcement of GNPs. Additionally, we noticed higher thermal stability of nanocomposites due to the faster heat-conducting path developed in the nanocomposites by the presence of GNPs. However, observed agglomeration of GNPs at higher concentrations and poor wetting with ABS led to the deterioration of the mechanical properties of the nanocomposites. Moreover, 350 µm thick nanocomposite films were manufactured by compression molding, followed by the extrusion method, and we investigated their electrical conductivity, magnetic permeability, permittivity, and electromagnetic-wave-shielding effectiveness. The developed nanocomposites showed improved conductivity and effective electromagnetic wave shielding by absorption. The 15 wt.% GNP-reinforced ABS composite film showed a maximum shielding effectiveness of 30 dB in the X-band.

Flexible MXene‐Based Composite Films for Multi‐Spectra Defense in Radar, Infrared and Visible Light Bands

AbstractSimultaneously developing protective electronics film for multi‐spectra, including the radar, infrared (IR), and visible ranges, for both the military and civilian sectors is extremely challenging. The existing multi‐spectra‐compatible materials mainly concentrate on either the radar/IR or IR/visible bands, trailing the rapid evolution of advanced devices for monitoring electromagnetic signals. Here, it is designed and fabricated an ultra‐thin MXene‐based composite film (20 µm) containing black phosphorus (BP) and Ni chains (M‐B‐M(Ni)) with integrated highly efficient thermal IR stealth, visible light absorption, and electromagnetic wave shielding. M‐B‐M(Ni) exhibits an extremely low IR emissivity of 0.1, decreasing the radiation temperature difference between the surrounding environment and target device. BP offers a high solar absorptance of 80%, which guarantees energy conversion from visible light to heat. Moreover, the absorption proportion of the electromagnetic shielding effectiveness for M‐B‐M(Ni) is 16% higher than that of pure MXene films (68.7%), owing to the improved magnetic loss by decoration with magnetic Ni chains. Due to the combined merits of MXene, BP, and Ni chains, M‐B‐M(Ni) opens an avenue for the construction of advanced multi‐spectra compatible materials for versatile applications in thermal IR stealth, electromagnetic wave shielding, and energy transformation.

Enhancement of Electromagnetic Wave Shielding Effectiveness by the Incorporation of Carbon Nanofibers-Carbon Microcoils Hybrid into Commercial Carbon Paste for Heating Films.

Carbon microcoils (CMCs) were formed on stainless steel substrates using C2H2 + SF6 gas flows in a thermal chemical vapor deposition (CVD) system. The manipulation of the SF6 gas flow rate and the SF6 gas flow injection time was carried out to obtain controllable CMC geometries. The change in CMC geometry, especially CMC diameter as a function of SF6 gas flow injection time, was remarkable. In addition, the incorporation of H2 gas into the C2H2 + SF6 gas flow system with cyclic SF6 gas flow caused the formation of the hybrid of carbon nanofibers-carbon microcoils (CNFs-CMCs). The hybrid of CNFs-CMCs was composed of numerous small-sized CNFs, which formed on the CMCs surfaces. The electromagnetic wave shielding effectiveness (SE) of the heating film, made by the hybrids of CNFs-CMCs incorporated carbon paste film, was investigated across operating frequencies in the 1.5-40 GHz range. It was compared to heating films made from commercial carbon paste or the controllable CMCs incorporated carbon paste. Although the electrical conductivity of the native commercial carbon paste was lowered by both the incorporation of the CMCs and the hybrids of CNFs-CMCs, the total SE values of the manufactured heating film increased following the incorporation of these materials. Considering the thickness of the heating film, the presently measured values rank highly among the previously reported total SE values. This dramatic improvement in the total SE values was mainly ascribed to the intrinsic characteristics of CMC and/or the hybrid of CNFs-CMCs contributing to the absorption shielding route of electromagnetic waves.

Polarization-sensitive broadband bidirectional absorber in the optical communication band

Here, we propose a polarization-sensitive broadband bidirectional plasmonic absorber in the optical communication band. The proposed structure can achieve an excellent absorption performance (>90%) under the TE wave illumination at the wavelength range from 1370 nm to 1630 nm within an incident angle up to 45°. The analysis of the electromagnetic field distribution reveals that the coupling of propagating surface plasmons resonance and local surface plasmon resonance dominates the perfect absorption performance. The symmetry of the structure determines that the device has the characteristics of bidirectional absorption. In addition, the effect of interlayer alignment accuracy on absorption performance is discussed, and the result indicates that low alignment accuracy is allowed. The bidirectional broadband plasmonic absorber shows a promising prospect in electromagnetic wave shielding, optical sensors, photodetectors, and communication.

Absorption-dominated electromagnetic interference shielding assembled composites based on modular design with infrared camouflage and response switching

Absorption-dominated electromagnetic interference (EMI) shielding materials are ideal for preventing electromagnetic pollution, but they suffer from complex structural design, poor performance stability, and narrow operating bands. Here, silica/carbon nanotubes/polyimide-silver nanowires/cellulose nanofibers (SiO2/CNTs/PI-AgNWs/CNF) composites are prepared based on the principle of split conductive modular design. According to the use requirements, the electromagnetic module is reasonably assembled, thus achieving a high degree of unity in electromagnetic wave absorption and shielding. In detail, the SiO2/CNTs/PI foam with progressive long channel structure has good impedance matching and provides excellent electromagnetic wave absorption. The highly conductive AgNWs/CNF film ensures excellent EMI shielding performance. The reflection shielding effectiveness (SER) is as low as 0.023 dB at an average EMI SE of 110 dB for the assembled composite, corresponding to an ultra-low reflectivity (R) of 0.00538. In addition, the assembled composite also has an autonomous switching function between infrared camouflage and infrared response, due to the low infrared emissivity characteristic and Joule heating effect of AgNWs/CNF film, as well as the thermal insulation properties of SiO2/CNTs/PI foam. This flexible work will stimulate adaptive applications of EMI shielding materials in radar stealth and infrared camouflage environments.

Multifunctional graphene/carbon fiber aerogels toward compatible electromagnetic wave absorption and shielding in gigahertz and terahertz bands with optimized radar cross section

Lightweight absorption-dominated electromagnetic interference (EMI) shielding materials with multifunctional integration of multiband absorption, mechanical durability and thermal insulation are urgently required in the practical application of next-generation communication technology combined with flexible electronics. In this work, ultralight and mechanically durable graphene/carbon fiber composite aerogels (CGAs) are synthesized via solvothermal reaction and freeze-drying. The as-prepared CGAs demonstrate excellent compatible electromagnetic wave absorption and shielding performance in both gigahertz (GHz) and terahertz (THz) bands without addition of magnetic component. Specifically, a broad efficient absorption bandwidth of 8.72 GHz at 2–18 GHz and a high mean absorptivity of 97.4% at 0.3–1.5 THz are achieved, respectively. Furthermore, absorbing coatings with CGAs have been proved to contribute to remarkable radar cross section reduction of 39.06 dBm2 by computer-assisted simulation. Additionally, the compressible CGA demonstrates superior and stable EMI shielding performance under in-situ compression. The EMI shielding effectiveness exceeds 35 dB in X-band when a compression ratio of 78.9% is applied. Moreover, CGAs are thermally insulating and self-extinct, making them reliable in practical application. This work provides a series of promising multifunctional lightweight EMI shielding materials for future high-frequency wireless communication.

Joule-heated flexible carbon composite towards the boosted electromagnetic wave shielding properties

Joule-heated flexible carbon composite towards the boosted electromagnetic wave shielding properties