Efficient Electromagnetic Wave Absorption Research Articles

Synthesis of nano-diamond modified Ti3C2Tx MXene heterostructure for enhanced electromagnetic wave absorption

The highly efficient electromagnetic wave (EMW) absorption materials are considered a promising approach to combatting electromagnetic radiation pollution. We synthesized a novel heterostructure 2D Ti3C2Tx MXene composite film modified by 0D nano-diamond (ND) particles using simple mechanical stirring and a vacuum filtration method. Subsequently, we investigated its microstructure and EMW absorption properties. The ND modification not only regulated the impedance matching of the composite films but also enhanced the diversity of EMW losses, demonstrating excellent microwave absorption performance. With a 40 wt% ND content, the minimum reflection loss (RLmin) of the films reached −43.0 dB, corresponding to a film thickness of 2.5 mm. This study explored a novel and promising microwave absorption film, expanding the application of diamond in microwave absorption, and addressing the theoretical gap in diamond-enhanced MXene microwave absorption performance.

Utilization of waste biomass to produce SiO2/SiC nanowires with efficient electromagnetic wave absorption performance

Utilization of waste biomass to produce SiO2/SiC nanowires with efficient electromagnetic wave absorption performance

In situ formation SiC nanowires on loofah sponge-derived porous carbon for efficient electromagnetic wave absorption

A lightweight, heterogeneous, three-dimensional network-structured composite has been meticulously developed with the specific goal of optimizing impedance matching and elevating electromagnetic wave absorption properties. SiC nanowires-carbon composites were synthesized through a novel process involving combined carbothermal reduction and chemical vapor deposition, utilizing loofah sponge as the foundational material. Accessible and cost-effective organosilane waste was applied as the silicon source. The resulting composites manifest exceptional electromagnetic wave absorption performance with a minimum reflection loss of − 46.34 dB and a wide effective bandwidth of 3.84 GHz at a thin thickness of 1.9 mm. Superior electromagnetic wave absorption is attributed to synergistic interplay of multiple interfacial polarizations, dipole polarization, conductive losses, and multiple reflections and scattering. This work presents an innovative pathway toward fabricating highly efficient electromagnetic wave-absorbing materials while effectively repurposing recycled waste.

Multifunctional carbon nanotube arrays on kapok-derived carbon microtube composites for efficient electromagnetic wave absorption and Cu(II) removal

To cope with different environments of application, electromagnetic wave absorption (EWA) materials with multifunctionality have attracted a wide range of interests. And excessive heavy metal ions in aqueous solutions seriously affect people’s health and pose a major challenge to environmental safety. In this study, carbon microtube/carbon nanotube (CMT/CNT) composites were fabricated via carbonization and chemical vapor deposition (CVD) methods. The CNT wrapped with cobalt nanoparticles were grown in situ on the CMT which derived from kapok fiber. By varying the concentration of cobalt precursors, the EWA and Cu(II) adsorption performances of CMT/CNT can be efficiently tuned. Optimizing the cobalt content to 2 wt% resulted in a minimum reflection loss (RL) of −66.14 dB at a matching thickness of 1.91 mm, with an effective absorption bandwidth (EAB) of 5.35 GHz. The adsorption capacity of Cu(II) by the CMT/CNT composite can reach 102.01 mg/g when the initial Cu(II) concentration is 500 mg/L. This research not only shows great promise for applications in the field of EWA materials but also holds significant potential for heavy metal ion removal and as a catalyst carrier, among other areas.

Graphene Aerogel Composites with Self-Organized Nanowires-Packed Honeycomb Structure for Highly Efficient Electromagnetic Wave Absorption

HighlightsA new strategy for elaborate regulation of microstructure was successfully introduced by the ice template‑assisted 3D printing and chemical vapor deposition strategy, including graphene nanoplate/silicon carbide nanowires hierarchical porous structure and graphene nanoplate/boron nitride composite heterogeneous interface.The composite exhibits excellent electromagnetic wave absorption performance with an RLmin of -37.8 dB and an EABmax of 9.2 GHz (from 8.8 to 18.0 GHz) at 2.5 mm. And the high-temperature absorption stability makes it a promising absorber candidate under high temperature and oxidizing atmosphere.

Ultrasound-assisted freeze-drying graphitization process for the fabrication of two-dimensional carbon/Fe3O4 composite aerogels for microwave absorption

Magnetic Fe3O4 materials have received attention from researchers due to their significant wave absorption potential, but there are limitations to their efficient electromagnetic wave absorption and lightweight applications. Combining materials with dielectric properties to optimize the performance of Fe3O4 has become one of the research directions. In particular, carbon nanomaterials, such as graphene, show great application prospects in the field of microwave absorption due to their physical properties. To improve the impedance mismatch issue of graphene, researchers consider combining it with magnetic nanoparticles. Commercial applications require materials that are cost-effective, easy to produce, and environmentally sustainable, driving research on novel 2D carbon materials. In this study, 2D carbon materials were prepared by ultrasound-assisted freeze-drying/graphitization process using polymers as precursors, which simplifies the preparation process and avoids the use of expensive sacrificial templates and catalysts. The 2D carbon materials prepared by this method were used as the dielectric component in the wave-absorbing composites, and the nano effect was utilized to significantly improve the microwave absorption properties of the materials. The maximum reflection loss of the prepared graphite nano-aerogel reaches −84.16 dB and the EAB reaches 3.74 GHz. In addition, by adding Fe3O4 nanoparticles and applying an ultrasonic field for dispersion in the freeze-drying process, the nanoparticle agglomeration is effectively prevented, which provides a simple and efficient pathway for the preparation of nanocomposites.

Mesoporous carbon spheres modified with atomically dispersed iron sites for efficient electromagnetic wave absorption

Carbon materials have obtained some achievements in electromagnetic wave (EMW) absorption owing to their excellent electrical conductivity and low density. However, poor impedance matching and high electrical conductivity limit their EMW absorption properties. Metal single atoms absorbers have garnered considerable attention in EMW absorption, largely due to the high metal availability and special coordination structure, but the modulation of the EMW absorption properties still needs to be improved. Herein, atomically dispersed Fe sites embedded into the N-doped mesoporous carbon spheres (Fe–SAs/NC) were synthesized through a facile coordination-assisted polymerization assembly strategy without acid leaching treatment. Benefitting from abundant mesoporous structure, the Fe–SAs/NC displays large specific surface area (339 m2 g−1) and optimized impedance matching, which results in an effective reduction of the absorber density. The homogeneously dispersed Fe single atoms (Fe–SAs) on the carbon skeleton lead to the improvement in conduction and dipole polarization losses of Fe–SAs/NC, which endows Fe–SAs/NC with exceptional EMW absorption properties. Experimental results indicate that Fe–SAs/NC displays desirable EMW absorption properties with the minimal reflection loss of −52.5 dB at 2.8 mm and the effective absorption bandwidth of 4.8 GHz. The study provides valuable insights for the development of carbon materials modified with atomically dispersed metal sites to achieve high-efficient EMW absorbers.

Fabrication of core–shell nickel ferrite@polypyrrole composite for broadband and efficient electromagnetic wave absorption

Herein, nickel ferrite@polypyrrole (NiFe2O4@PPy) composite was prepared by a simple two-step route of solvothermal synthesis and in-situ oxidation polymerization reaction. The results of micromorphology analysis showed that the obtained NiFe2O4@PPy composite had a unique core–shell structure, good magnetic performance and electrical conductivity. Furthermore, the as-prepared magnetic/conductive NiFe2O4@PPy composite exhibited notably enhanced electromagnetic wave (EMW) absorption performance than pure NiFe2O4 and PPy. When the filling ratio was 17.5 wt% and the matching thickness was 2.24 mm, the optimal minimum reflection loss (RLmin) of −56.25 dB and a broad effective absorption bandwidth (EAB) of 5.2 GHz were achieved for NiFe2O4@PPy composite. With slightly increasing the matching thickness to 2.6 mm, the maximum EAB of 7.12 GHz could be reached. Additionally, the probable EMW absorption mechanism was elucidated. Therefore, this work could provide a valuable reference for the preparation of magnetic ferrite/conductive polymer composites as broadband and high-efficiency EMW absorbers.

Control of dielectric properties of composite materials by editing low dielectric ceramics with anchored structure

Extensive research over the impact of the content of a particular constituent in composites on their electromagnetic wave-absorbing performance has been witnessed. However, an accurate summary regarding the impact of ceramics’ dielectric constant on electromagnetic absorption performance of ceramic/graphene composites is still ad referendum. In this paper, a series of low-dielectric ceramics were synthesized by precisely controlling the proportion of boric acid and subsequently integrated with reduced Graphene nanosheets (RGNSs) to fabricate ceramic/RGNSs composites for efficient electromagnetic wave absorption. The amorphous range of ceramics, which is affected by the boric acid content, controls the dielectric properties that subsequently affect the absorption performance. Increasing the amorphous range of ceramics was found to result in an increase in both maximum value and stability of the actual component of complex permittivity for SiBON/RGNSs composite material. Additionally, tangent values at X and Ku bands also exhibited an increase, leading to an augmented microwave absorption performance (maximum absorption bandwidth: 4.94 GHz; minimum reflection loss: −50.45 dB).

Spontaneous Orientation Polarization of Anisotropic Equivalent Dipoles Harnessed by Entropy Engineering for Ultra-Thin Electromagnetic Wave Absorber

HighlightsThe strengthening mechanism of spontaneous orientation polarization of anisotropic equivalent dipoles within high-entropy alloys (HEAs) is proposed for enhancing dielectric attenuation of HEAs.The source of carbon supporter is expanded to the biomass category, which can construct the shell-core heterointerfaces with HEAs by means of a reformative carbothermal shock method.The sample carbonized cellulose paper/HEAs-Mn2.15 achieves efficient electromagnetic wave absorption of -51.35 dB at an ultra-thin thickness of 1.03 mm.This work combines theoretical calculations and electromagnetic simulations to propose feasible strategies for the design and application of electromagnetic functional devices such as ultra-wideband bandpass filter.

Construction of rGO/MOF-derived CNTs aerogel with multiple losses for multi-functional efficient electromagnetic wave absorber

Graphene aerogels have attracted increasing attention in electromagnetic wave (EMW) absorption due to their ultra-low density and excellent dielectric performance. However, pure graphene aerogels have limited loss mechanisms, and it remains a challenge to introduce multiple loss mechanisms while maintaining lightweight. Here, reduced graphene oxide/metal organic framework (MOF)-derived carbon nanotubes (rGO/MD@CNTs) aerogels are successfully constructed by uniformly compositing GO and MOF particles by hydrothermal treatment and further in-situ growing CNTs by chemical vapour deposition method. GO and MOF particles form strong bonding sites due to their interaction to construct the aerogel with excellent mechanical property, while magnetic loss is also introduced. The MOF-catalyzed CNTs not only contribute to the formation of interface and dipole polarizations, but also effectively regulate the conductivity to improve impedance matching. rGO/MD@CNTs aerogel integrates multiple losses and optimal impedance matching. With a filling ratio of 6 wt%, the aerogel exhibits an excellent reflection loss of −51.6 dB and a wide effective absorption bandwidth of 5.9 GHz. In addition, the aerogel shows good thermal stability and antifreeze properties. Therefore, this work provides an effective strategy for obtaining the aerogel with multiple losses for efficient EMW absorption, demonstrating the potential applications of rGO/MD@CNTs aerogel in complex environments.

Multifunctional SiC nanowire aerogels with efficient electromagnetic wave absorption for applications in complex environments

In the digital age, with rapid advancements in electromagnetic (EM) technology, electromagnetic pollution has emerged as a significant concern. Traditional electromagnetic wave (EMW) absorption materials, however, are constrained by their limited application range, inadequate physicochemical stability, and inferior mechanical strength, hindering their further development and application. Consequently, there exists a demand for an EMW absorber that not only incorporates multiple functionalities but also retains essential physicochemical characteristics. In this context, this study introduces an ultralight (∼12 mg cm⁻³) and multifunctional SiC nanowire aerogel (SNWA), synthesized through a direct chemical vapor deposition (CVD) technique. The resulting SNWA demonstrates exceptional elasticity, outstanding mechanical durability, and high thermal stability at increased temperatures. Additionally, the enhanced SNWA shows improved hydrophobic properties, facilitating its use in highly humid conditions. The SNWA material also presents remarkable EMW absorption efficiency, with a minimum reflection loss of −50.6 dB and an effective absorption bandwidth of up to 7.7 GHz. The straightforward CVD synthesis and surface modification technique ensure the SNWA's durable and efficient performance in demanding environments.

Fe3C/Fe implanted hierarchical porous carbon as efficient electromagnetic wave absorber

The rapid development of communication technology has led to severe microwave pollution, which presents a challenge for microwave-absorbing composites. Current research suggests achieving superior microwave absorption requires the use of multi-component operation and ingenious structural design. Consequently, the present study has prepared continuous porous carbon (CPC) materials doped with large amounts of Fe3C/Fe nanoparticles (Fe@CPC) using carbonization and acid etching. By balancing the advantages of the above strategies, it is possible to address issues such as poor impedance match, single loss capacity, easy oxidation of magnetic metals/alloys, and the limited absorption bandwidth of conventional absorbing materials at the same time. The material exhibits a minimum reflection loss of −23.2 dB with an efficient absorption range of 5.3 GHz at 1.9 mm at a filler content of just 10 wt% in the paraffin matrix. In this paper, the samples with a continuous porous structure were prepared by a simple method, and the properties were excellent due to the appropriate preparation method and the synergistic effect of the multi-component composite. The porous structure facilitates the presence of a considerable number of active sites, which enables the loading of a substantial quantity of metal ions. Furthermore, nanoparticles are capable of aggregating and dispersing on the surface. This paper presents a theoretical framework for understanding the synergistic effect of microwave radiation through interfacial polarization and micro-scale magnetic interaction. Nevertheless, there are still obstacles to overcome in terms of achieving precise control over the structural design and ensuring the compatible integration of metal components.

The cation exchange driving multi-phase regulation in Co7Fe3/Co@NC for enhanced broadband electromagnetic wave absorption

Phase engineering offers distinctive advantages in designing efficient electromagnetic wave (EMW) absorbers. The manipulation of the interaction and arrangement of different multi-phase systems enables the achievement of more precise EMW absorption. However, the transition mechanism from single metal phases to metal/alloy phases has not yet been fully revealed. Here, we employ multiphase engineering driven by cation exchange reactions to finely control the proportion of Co/Co7Fe3 phases and regulate electromagnetic parameters. The introduction of cavities and heteroatoms through cation exchange enables optimized defect distribution and composition, which enhances both impedance matching and electromagnetic attenuation capabilities. Specifically, we yield hollow Co7Fe3/Co@N-doped carbon (H-Co7Fe3/Co@NC) embedded in high-crystallinity graphite carbon after high-temperature pyrolysis, which promotes significant electron transfer between phases, thus enhancing conduction and polarization losses. H-Co7Fe3/Co@NC exhibits ultra-strong reflection loss (RL) of −59.70 dB at 9.37 GHz and achieves broadband absorption of 6.01 GHz at 2.1 mm. This study highlights the influence of Co7Fe3/Co heterogeneous structures on absorption performance and validates the electromagnetic response mechanism of multi-phase heterostructures through COMSOL finite element simulation analysis. Thus, this work paves the way for applying multi-phase engineering driven by cation exchange reactions for advanced absorbers.

MOF derivatives anchored to multichannel hollow carbon fibers with gradient structures for corrosion resistance and efficient electromagnetic wave absorption

With the rapid development of 5G technology and the interconnection of industrial production, electromagnetic pollution has become a serious problem. Achieving lightweight and controllable loads of absorbers while obtaining corrosion-resistant absorbers with high electromagnetic response properties is still considered a huge challenge. In this work, carbon fiber with a multichannel hollow structure is obtained by PAN/PS hybrid electrospinning and subsequent high-temperature roasting process. The spatial structure inside the carbon fiber plays an active role in optimizing the impedance matching characteristics of the absorber. In addition, bimetallic metal-organic frameworks (MOFs) derivatives are obtained by a precisely controlled ion exchange as well as a high-temperature gas-phase selenization process. The resulting introduction of a non-homogeneous interface induces interfacial polarization and improves the absorption behavior of the absorber. The analysis of the experimental results shows that the electromagnetic wave (EMW) absorption performance can be effectively enhanced due to the mechanisms of interface polarization and dipole polarization. The prepared NiSe/ZnSe/MHCFs composite can obtain excellent EMW absorption properties in C, X, and Ku bands by adjusting the thickness. Structural design and component modulation play a crucial role in realizing the strong absorption and wide bandwidth of the absorber. Radar cross-section calculations indicate that NiSe/ZnSe/MHCFs have tremendous potential in practical military stealth technology. And the prepared composite coating can provide periodic corrosion resistance to Q235 steel sheet when dealing with complex and extreme environments.

Construction of polymer-derived double transition metal compound/carbon matrix nanocomposites for efficient electromagnetic wave absorber

As typical dielectric materials, transition metal compounds have a broad potential in the field of stealth, but their application is still hampered by poor conductivity. In this study, based on the mechanism of electrostatic self-assembly of heteropolyacids and organic ligands, the electrostatic structures obtained after the introduction of different heteropolyacids into the conductive phase pyrrole are carbonized. On the one hand, the as-prepared transition metal compounds/carbon matrix nanocomposites produce synergistic effects and optimize impedance matching, and on the other hand, the formation of the abundant heterogeneous interfaces as well as the doping of the N, P heteroatoms induce the generation of interfacial polarisation and dipole polarisation, all of which provide the opportunities to produce composites with enhanced electromagnetic wave absorption properties. Unsurprisingly, the best synthesised sample, Mo2C/W2C/NPC, exhibits a significantly improved electromagnetic wave absorption performance, with an effective bandwidth of 5.7 GHz at a matched thickness of 2.5 mm, where the minimum reflection loss value of −54.5 dB is also achieved. The total effective bandwidth of the Mo2C/W2C/NPC-35 wt% is up to 10.5 GHz (7.3–17.8 GHz) via adjusting the matching thickness in the range of 1.7–3.5 mm. Therefore, this study reflects that dual transition metal compound/carbon based composite wave-absorbing materials provide a new material basis for the construction of high-performance absorption materials.

Biological template hydrothermal synthesis of hollow La-doped one-dimensional CaMnO3 fibers and their enhanced microwave absorption performance

The advancement of military technology, 5G communication, and electronic equipment has increased the demand for efficient electromagnetic wave absorption materials. Calcium manganate (CaMnO3) is a commonly used dielectric absorber due to its excellent dielectric polarization effect. However, traditional ceramic materials like CaMnO3 have low conductivity, making it difficult to achieve impedance matching and electromagnetic loss simultaneously. In this work, to address this issue and create ideal wave-absorbing materials, one-dimensional La-doped CaMnO3 materials were synthesized using a simple biological template hydrothermal method. By studying the relationship between doping content and electromagnetic parameters, it was found that the La-doped CaMnO3 material exhibited excellent electromagnetic wave absorption properties, with a minimum reflection loss (RLmin) of −73.62 dB and a maximum effective absorption bandwidth of 3.3 GHz in the X-band. The introduction of La elements, which have different electronegativities from Ca ions, altered the electron cloud distribution in the sample, leading to the formation of electric dipoles that disrupt charge distribution and dissipate electromagnetic waves. The dielectric loss in fibrous La-doped CaMnO3 is mainly due to interfacial polarization. The fibrous structure allows for increased contact area with the air medium, while the porous structure introduces air bubbles that alter the dielectric properties between the sample and the air medium. This not only enhances impedance characteristics to some extent but also triggers interfacial polarization. Both of these factors help improve the material's ability to absorb electromagnetic waves. The successful creation of this one-dimensional absorbing material opens up possibilities for developing new one-dimensional absorbing materials using a straightforward method.

Multi-interface engineering design of nitrogen-doped bamboo-based carbon/Fe/Fe3C composite electromagnetic wave absorber based on honeycomb-ant nest-like structure

The integration and development of artificial intelligence (AI) and 5G communication technology have brought tremendous changes to human society. How to create a green electromagnetic environment has attracted people's attention. Rich heterostructure design based on interface engineering is considered an effective means of obtaining efficient electromagnetic wave absorbers. In this work, we have achieved innovative design of nitrogen doped carbon/Fe/Fe3C multi-interface heterostructures. The delignification modification of bamboo enriches the cellular pore channels, effectively regulates the loading of Fe3+and the diffusion binding of pyrrole molecules and promotes the deep construction of multi-layer heterogeneous interfaces. Further in-situ pyrolysis resulted in the formation of abundant honeycomb ant nest like structural pores and nitrogen doped multiphase heterostructure interfaces. Provided the best multi-component loss mechanism and impedance matching for the material, improving the overall dielectric and interface polarization effects of the material. Therefore, the obtained absorbent exhibits satisfactory electromagnetic wave absorption performance at a low load of 20 %, with an effective absorption bandwidth of 6.5 GHz (1.85 mm). This work provides new ideas for the high-value utilization of biomass in nature, optimization and innovative design of multi-level pore structures for microwave absorbers.

FeSiBCuNbZr amorphous composites decorated with SiO2 and TiO2(B) (bronze phase TiO2) for efficient electromagnetic wave absorption

The application of Fe-based amorphous microspheres in high-performance electromagnetic wave absorbing materials is significantly limited by a single loss mechanism. Utilizing interfacial engineering and magnetic-dielectric synergistic effect is a viable approach to enhance microwave absorption. In this work, FeSiBCuNbZr amorphous microspheres were synthesized using single copper roller melt-spinning method and ball mill method. The finding reveals that the incorporation of SiO2 and TiO2(B) (bronze phase TiO2) shells notably enhances polarization loss and conductive loss. FeSiBCuNbZr@SiO2@TiO2(B) amorphous composites exhibited a minimum reflection loss value of −64.89 dB at a thickness of 2.17 mm and an effective absorption bandwidth (EAB) of 8.08 GHz covering 9–18 GHz at a thickness of 1.9 mm. The exceptional wave absorption performance is ascribed to the combined effect of magnetic loss in the FeSiBCuNbZr amorphous core and dielectric loss from the double-shell structure, while maintaining favorable impedance matching. This work provides a new core–shell FeSiBCuNbZr amorphous composites for efficient electromagnetic wave absorption.

A novel biomass-derived carbon@ZnO@ZnSe composites for efficient electromagnetic wave absorption

A novel biomass carbon-based ternary composite coated with ZnO and ZnSe was synthesized by activated carbonization and hydrothermal method. The composition, microstructure and electromagnetic wave (EMW) absorption performance and related mechanism of the composites were investigated in detail. The unique coating structure of lamellar ZnO and spherical ZnSe facilitates multiple reflection and scattering of EMWs, thereby enhancing the dissipation of EMW energy. Moreover, the incorporation of highly conductive ZnO and ZnSe not only enhances the polarization loss and conductivity loss of CBP@ZnO@ZnSe composites, but also improves the impedance matching, further optimizing the EMW absorption property greatly. The CBP@ZnO@ZnSe composites exhibited enhanced EMW absorption performance, characterized by a minimum reflection loss of −24.57 dB and an effective absorption bandwidth of 3.43 GHz at 2.89 mm, owing to the synergistic interplay of favorable impedance matching and attenuation ability. In addition, radar cross section simulation results further demonstrated that CBP@ZnO@ZnSe composites have good electromagnetic energy dissipation effect in practical applications. This study not only offers a simple and feasible method for preparing CBP@ZnO@ZnSe composites with excellent EMW absorption properties, but also serves as a reference for the research of ternary composites based on bio-derived carbon.