Outstanding Electromagnetic Wave Research Articles

Bimetallic two-dimensional metal-organic frameworks nanosheets derived bimetallic@C composite materials for effective electromagnetic wave absorption

The development of information technology has resulted in serious environmental pollution and health concerns due to electromagnetic wave radiation. There is a necessity to develop electromagnetic wave absorbers with strong absorption, wide bandwidth, thin thickness, light weight, and environmental friendliness. In this study, a series of Ni4Cux@C composite materials was synthesized through a simple coprecipitation and pyrolysis process. The morphology and absorption properties of the composite materials were precisely tuned by adjusting the ratio of the bimetallic Ni and Cu. The Ni4Cux@C two-dimensional nanosheets were designed to possess a high specific surface area and abundant porous structure, thus optimizing impedance matching. Its strong dielectric loss capability is collectively contributed to the excellent graphitization degree and multiple polarizations. Additionally, the dispersion of NiCu alloy nanodisks within the carbon matrix leads to the aggregation of a large number of free space charges at the heterogeneous interface, inducing the formation of interfacial polarization. The well-designed Ni4Cu2@C composite materials exhibit outstanding electromagnetic wave absorption capabilities, with the optimal reflection loss reaching -74.9 dB, and the maximum effective absorption bandwidth reaching 6.8 GHz (2.9 mm). This work provides an important research foundation for the rational design of a new generation of two-dimensional bimetallic electromagnetic waveabsorption materials.

The lightweight titanium dioxide/reduced graphene oxide composites prepared by hydrothermal method for microwave absorption

To solve electromagnetic pollution, microwave absorption materials with high performance have gained attention. Manipulating the impedance matching is an effective strategy to obtain the outstanding electromagnetic wave absorption material. In this work, a series of titanium dioxide/reduced graphene oxide (TiO2/RGO) composites were prepared by the hydrothermal method for microwave absorption. The relationship between the microstructure and microwave absorption performance of the composite was analyzed in detail. The impedance matching and attenuation ability of TiO2/RGO composites could be precisely manipulated by regulating the titanium dioxide content. The reflection loss and effective absorption bandwidth of the TiO2/RGO composite could reach −46 dB and 3.36 GHz (1.9 mm), respectively. Thus, the lightweight TiO2/RGO composite has the potential application in microwave absorption.

In situ loading of ZnO on hierarchical porous carbon derived from banana-peel waste to enrich mechanism for microwave absorption

Biomass has received widespread attention due to its easy availability, low cost, and environmental friendliness as an electromagnetic wave absorber candidate. Inspired by the natural porosity of biomass, the three-dimensional (3D) porous carbon materials derived from banana peels were prepared via coordination and pyrolysis carbonization. A conductive network of biomass-zinc complexes was constructed by introducing Zn2+ to coordinate with organic polymers. Hierarchical porous carbon/ZnO composites with a 3D skeleton network were obtained, which demonstrated outstanding electromagnetic wave absorption performance with an effective absorption bandwidth (EAB) of 6.72 GHz and the reflection loss (RL) of −44.18 dB. The banana peel-derived porous carbon (BPC) embedded with ZnO particles brings about conductive loss and interface polarization, further enriching the microwave loss mechanisms. This work offers a fresh idea for creating a green, sustainable, and high-value functional carbon-based composite material.

Preparation and performance of ultra-wideband high-temperature resistant calcium aluminate cement-based electromagnetic wave absorption cone structural composites

A novel high-temperature resistant calcium aluminate cement-based electromagnetic wave absorption composites were prepared using carbon fibers, Al2O3 hollow spheres, and expanded polystyrene spheres (EPS). EPS, as a pore forming agent, was oxidized as to form pores at high temperatures. The effects of carbon fibers doping levels and various high-temperature treatment on the permittivity of the composites from 0.3-18 GHz were investigated in detail. Additionally, a high-temperature resistant porous cone cement-based electromagnetic wave absorption structure was designed, and its microwave absorption mechanism was explored. The findings indicated that the permittivity of electromagnetic wave absorption composites exhibited stability even after undergoing high-temperature treatments below 350°C, while experiencing a decrease at 500°C. Following cyclic treatments at temperatures of 200°C and 350°C, the cone calcium aluminate porous cement-based composites still exhibited outstanding electromagnetic wave absorption performance, achieving reflection loss (RL) bandwidths below -30 dB of 17.4 GHz and 17.2 GHz, respectively, within the frequency range of 0.3-18 GHz. Furthermore, the RL of the composite from 4-18 GHz after 500°C treatment remained less than -50 dB. Thus, present work associated with the materials and structural design of calcium aluminate porous cone cement-based composites provided a potential insight into the high-temperature electromagnetic wave absorption engineering applications.

Flower-like Cu9S5 and magnetic NiCo@C particles synergize to build three-dimensional conductive networks for efficient electromagnetic wave absorption

To increase the use of sulfides in electromagnetic wave absorption, researchers are continuously developing thin semiconductor sulfide absorbers with significant absorption capacity and wide bandwidth. In this study, we synthesized NiCo@C/Cu9S5 materials with the dual loss mechanism (dielectric and magnetic losses) by evenly loading magnetic NiCo@C particles on flower-like Cu9S5 matrixes utilizing the magnetic derivatization technique for metal-organic frameworks (MOFs). The three-dimensional flower-like structures of the composites, intrinsic properties of the materials, and the resulting three-dimensional conductive network endow the material with multiple scattering and reflection, conduction loss, resonance, and eddy current properties. The synergistic effect of these loss pathways leads to the outstanding electromagnetic wave (EMW) absorption performance of the materials. The results show that the minimum reflection loss (RLmin) of NiCo@C/Cu9S5 can reach −52.83 dB when the matching thickness is 2.09 mm. Meanwhile, the maximum effective absorption band (EAB) is 5.1 GHz (12.3–17.4 GHz) at a matching thickness of 1.69 mm. Furthermore, the radar cross section (RCS) of the absorbers has been calculated by CST Studio Suite, demonstrating the ability of the absorbent coating to lower the RCS at different angles efficiently. These discoveries provide new insights for high-performance sulfide electromagnetic wave absorbers and contribute to electromagnetic wave energy storage and conversion studies.

Multifunctional carbon aerogels loaded with pea-pod-like carbon nanotubes for outstanding electromagnetic wave absorption performance

Although ordered porous carbon materials (PCMs) have shown promising potential in the field of electromagnetic wave absorption (EWA), creating multifunctional PCMs with outstanding microwave absorption performance remains a significant challenge. Herein, ordered porous carbon aerogels loaded with pea-pod-like nitrogen-doped carbon nanotubes (CNTs) were fabricated via orientation freeze-drying followed by high-temperature pyrolysis. The optimized aerogel exhibits extraordinary EWA performance with a broad effective absorption bandwidth of 7.68 GHz and exceptionally strong absorption of −91.58 dB at a low filling ratio of only 3 wt%, which is the largest absorption strength among all known aerogels to date. The exceptional EWA performance is attributed to the synergistic effect of abundant loss mechanisms resulting from a unique pod-like structure in ordered porous carbon aerogel, where nitrogen-doped CNTs encapsulate magnetic alloy nanoparticles. Optimized aerogel exhibits superior compressive elasticity, thermal insulation, and light weight, laying the groundwork for designing practical next-generation EWA materials.

Construction of multilayer carbon magnetic heterostructures on the surface of carbon fibers to improve the absorption performance

AbstractThis study utilizes the strong complexation effect of polydopamine on metal ions and constructs multilayer carbon magnetic heterostructures on the surface of carbon fibers through the in situ reduction method, thereby obtaining a new type of multilayer carbon‐based composite absorbing material. The absorption properties at different layers were analyzed and compared through various characterization methods. Finally, the double‐layer structure demonstrated outstanding electromagnetic wave absorption characteristics, exhibiting a wide effective absorption bandwidth of 7.24 GHz and robust absorption of −44.48 dB, all within a mere thickness of 3.5 mm. Therefore, excellent market prospects for this material are anticipated.Highlights A multilayer carbon magnetic heterostructure absorbing material was constructed on micrometer‐scale carbon fibers. The test results show that a wide effective absorbing bandwidth of 7.24 GHz and a minimum reflection loss of −44.48 dB are obtained when the composite thickness is 3.5 mm. The prepared multilayer absorbing composites can adapt to a variety of application scenarios and have excellent application prospects in the industry. The self‐polymerization of dopamine and complexation of metal ions were used to construct multilayer absorbing materials, and the dielectric loss and magnetic loss capacity of the carbon fibers improved.

Single‐Atom Nanozyme‐Like Lanthanum Moieties for High‐Performance Electromagnetic Energy Absorption

AbstractSingle‐atom (SA) nanozymes have unprecedented physicochemical performance due to their integrated merits of both atomically dispersed metal atoms and bio‐enzymes. However, the structure‐function relationship between the SA nanozyme‐like structure and its dielectric performance is still unclear. Furthermore, controllable synthesis of SA nanozyme‐like structures remains challenging due to their unique five‐coordinated configurations. Here, a dicyandiamide‐mediated pyrolysis strategy is proposed to anchor five nitrogen‐coordinated lanthanum (La)–N5 moieties on interconnected N‐doped graphene nanocages (La‐N5/ING). Theoretical predictions indicate that the spatially coordinated La–N5 moieties exhibit significantly enhanced conduction loss and polarization loss compared to La–N4 moieties, as evidenced by the experimental results. Moreover, the polydimethylsiloxane‐coated chemically cross‐linked film constructed by the La‐N5/ING and aramid nanofibers has outstanding electromagnetic wave (EMW) absorption performance with an effective absorption bandwidth (EAB10) of 6.24 GHz at a thickness of merely 2.0 mm, outperforming those of most reported carbon‐based films. Importantly, the film also has excellent flexibility, hydrophobicity, mechanical strength, and structural stability, ensuring its application potential in practical environments. These findings provide crucial insights into the microscopic environment of SA on the dielectric properties of their host materials, and a critical method for the preparation of multifunctional films with spatial coordinated SA.

Enhanced electromagnetic wave absorption in YAG-modified SiC foam

Electromagnetic technology applications are escalating, leading to increased human exposure to electromagnetic radiation. In addressing the challenges posed by this radiation, electromagnetic wave absorbing materials stand out due to their distinguished properties. This study focused on developing porous fibrous SiC three-dimensional (3D) foams. These were synthesized by freeze-drying SiC nanofiber dispersions followed by high-temperature sintering. Measurements demonstrated that the resulting SiC foams possess a relatively low density, approximating 0.1 g cm−3. Upon microscopic analysis, it became evident that the foam's porous structure is predominantly made up of SiC fibers intermixed with yttrium aluminum garnet granules. These tailored SiC foams delivered outstanding electromagnetic wave absorption characteristics, recording a minimum reflection loss value of −63 dB. Furthermore, an expansive effective absorption bandwidth of 6.9 GHz (spanning from 9.3 to 16.2 GHz) was noted for a sample thickness of 3.15 mm. Several factors contribute to this high absorption efficacy, including multiple reflections and both interface and dipole polarizations. It is also worth noting that the SiC foam displayed commendable oxidation resistance when exposed to elevated temperatures. Cumulatively, these findings underscore the promising potential of porous fibrous SiC 3D foams in electromagnetic wave absorption applications, especially in extreme conditions.

Urchins CuCo2S4/Carbon composites with abundant defects and hetero-interfaces for optimized impedance matching and broadened effective band width

This work adopts a composite strategy combining “large anisotropic structure” and “strong dielectric material”, which is a pioneer work reported on urchins CuCo2S4/C absorber. An environmentally friendly (eco-friendly) CuCo2S4/C composites were prepared through a facile route including an ion exchange method and a simple physical grinding process. The resultant CuCo2S4/C composites exhibit an urchins-like morphology with carbon nanoparticles anchored randomly on the tentacles of the urchins. The urchins CuCo2S4/C composites display an optimal reflection loss value of −44.2 dB at the thickness of 2.2 mm, and the effective bandwidth with RL < −10 dB reaches 7.12 GHz at a thickness of 2.4 mm. The outstanding electromagnetic (EM) wave absorption performance is mainly benefited from the synergistic effects between the anisotropic structure of CuCo2S4 and conductive carbon particles. By adjusting the component ratio during the grinding process, an optimized combination of conduction loss and polarization loss can be achieved, and the impedance matching level can be regularly controlled and improved while increasing the effective absorption bandwidth. These results indicate that the sea urchin CuCo2S4/C composite material designed in this work can serve as an ideal candidate for high-performance electromagnetic wave absorption and has certain reference significance for the development of more sulfide semiconductor based absorbing materials.

Graphene‑Assisted Assembly of Electrically and Magnetically Conductive Ceramic Nanofibrous Aerogels Enable Multifunctionality

AbstractCeramic aerogels are gaining increasing attention due to their low density, high‐temperature resistance, and excellent chemical stability. However, conventional ceramic aerogels are hindered by their intrinsic brittleness and limited dielectric properties, which restrict their scalable manufacturing and multifunctional applications. Here, ultralight, biomimetic porous, electrically and magnetically conductive ceramic nanofibrous aerogels composed of silicon dioxide (SiO2) nanofibers, graphene, and metal–organic framework (MOF) derivatives are prepared through an ice‐templating freeze‐casting followed by annealing approach. The renewable SiO2 nanofibers form robust bonding points with graphene, constructing interconnected high‐porosity aerogels with good mechanical resilience. This allows for efficient integration of MOF‐derived magnetic nanoparticles associated with a synergistic mechanical enhancement. The synergies of the dielectric and magnetic components, combined with the uniformly arranged sheet‐like cell walls which facilitate the outstanding electromagnetic wave absorption performance. Moreover, the hydrophobic ceramic aerogels showcase excellent magnetothermal conversion, contributing to the application in wireless therapy, antibacterial, and magnetothermal deicing. Furthermore, the nanofibrous aerogels exhibit good thermal stability and insulation properties, rendering them highly suitable for thermal management devices in extreme conditions. With the renewable, convenient, and scalable manufacturing method, these multifunctional ceramic nanofibrous aerogels thus hold great promise in electromagnetic protection, wireless heating, and next‐generation thermal management devices.

A multi-layer design of hexaferrite decorated graphene derivatives incorporated PVDF nanocomposite films; understanding the role of GO/rGO for outstanding electromagnetic wave absorption at microwave frequencies

Y-type strontium hexaferrite (SrY) nanoparticles are prepared by sol gel synthesis route and the nanoparticles are taken with graphene oxide (GO) and reduced graphene oxide (rGO) separately to prepare SrY/GO and SrY/rGO binary nanofillers. These two binary nanofillers reinforced PVDF mono-layer and multi-layer nanocomposite films (SrY/GO/PVDF and SrY/rGO/PVDF) have been prepared to analyse their complex permeability and permittivity, microwave absorption ability in 8–12 GHz (X-band) range. The crystallographic phase, chemical composition and the successful incorporation of the binary nanofillers inside PVDF was confirmed by XRD, XPS, RAMAN and FESEM analysis. J-E characterization of SrY/rGO/PVDF and SrY/GO/PVDF films verify the occurrence of conductive channels inside PVDF matrix for former and the development of polarization effect for later under external electric field. The high magnetization and coercivity of ∼28.24 emu/g and 1200 Oe at room temperature (RT) corresponding to SrY nanoparticles is favourable at incurring high magnetic losses for X-band. A remarkable enhancement in total shielding effectiveness (SET) from −63.16 dB to −82.53 dB has been observed for multi-layer SrY/GO/PVDF films as compared to its mono-layer structure. The majority of the contribution for SET is the shielding effectiveness due to absorption (SEA) (−60.11 dB) as compared to the same for reflection (SER) (−24.26 dB) at a matching frequency of ∼9.6 GHz. However, in case of SrY/rGO/PVDF films the predominance of SER over SEA has been observed. Therefore, our results could act as a pathway in devising a graphene/polymer-based magneto-electric laminated nanocomposite system for lightweight and customized microwave shield within the X-band frequency.

Fabricating FeS2 and CuFeS2 microspheres embedded into biomass derived porous carbon with excellent microwave absorption

The design of carbon magnetic matrix nanocomposites with synergistic dielectric and magnetic losses is a significant research hotspot issue of wave-absorbing materials. In this paper, FeS2-CuFeS2@RPC composites were firstly fabricated by doping FeS2 on copper sulfide/rice husk derived porous carbon (Cu7.2S4@RPC), by controlling the amount of iron and sulfur sources. The study results indicate that the FeS2-CuFeS2@RPC-3 shows outstanding electromagnetic wave absorption performance. The minimum reflection loss (RLmin) of sample reaches −42.30 dB at 15.11 GHz (Ku band), corresponding to matching thickness of 1.7 mm, and the maximum effective absorption band (EAB) is 5.78 GHz at 1.9 mm. The synergistic interaction of the magnetic and dielectric components, which improves impedance matching, is responsible for this outstanding performance. The research of metal sulfide absorbing composite material scientific provide a new train of thought, and promote the development and application of metal sulfide composite absorbing materials.

Bimetallic porphyrin MOF derived CuIn particles/carbon composites as ideal microwave absorbers

CuIn/CN-600 shows a maximum RL of −78.42 dB at 13.84 GHz with an EAB of about 5.92 GHz at 1.92 mm.

Polyimide-based porous carbon and cobalt nanoparticle composites as high-performance electromagnetic wave absorbers.

This study successfully utilized a straightforward approach, choosing liquid-liquid phase separation to build a porous structure and synthesize composite absorbers based on polyimide-based porous carbon and cobalt nanoparticles (designated as PPC/Co-700 and PPC/Co-800). A fine porous structure was achieved as a result of the excellent heat resistance of polyimide resulting in an excellent electromagnetic wave absorption ability of PPC/Co composites. The results obtained clearly indicated that PPC/Co-700 and PPC/Co-800 exhibit a porous structure with coral-like pores, enhancing both impedance matching properties and microwave attenuation abilities. This improvement in impedance matching conditions and dissipation capability is attributed to the synergistic effect of dielectric loss induced by carbon and magnetic loss induced by Co nanoparticles. PPC/Co-700 showed the strongest absorption performance with a minimum reflection loss of -59.85 dB (30 wt% loading, thickness of 3.42 mm) and an effective absorption bandwidth (EABW, RL ≤ -10 dB) of 6.24 GHz (30 wt% loading, thickness of 2.78 mm). Therefore, this work provides a facile strategy for the development of a promising absorbing material with outstanding electromagnetic wave absorption performance.

Promoting Electromagnetic Wave Absorption Performance by Integrating MoS2@Gd2O3/MXene Multiple Hetero-Interfaces in Wood-Derived Carbon Aerogels.

Multi-component composite materials with a magnetic-dielectric synergistic effect exhibit satisfactory electromagnetic wave absorption performance. However, the effective construction of the structure for these multi-component materials to fully exploit the advantages of each component remains a challenge. Inspired by natural biomass, this study utilizes wood as the raw material and successfully prepares high-performance MoS2@Gd2O3/Mxene loaded porous carbon aerogel (MGMCA) composite material through a one-pot hydrothermal method and carbonization treatment process. With a delicate structural design, the MGMCA is endowed with abundant heterogeneous interface structures, favorable impedance matching characteristics, and a magnetic-dielectric synergistic system, thus demonstrating multiple electromagnetic wave loss mechanisms. Benefiting from these advantages, the obtained MGMCA exhibits outstanding electromagnetic wave absorption performance, with a minimum reflection loss of -57.5dB at an ultra-thin thickness of only 1.9mm. This research proposes a reliable strategy for the design of multi-component composite materials, providing valuable insight for the design of biomass-based materials as electromagnetic wave absorbers.

DLP–printable hyperbranched polyborosilazane for microwave absorbing SiBCN(O) ceramic metastructure

This work introduces a novel digital light processing (DLP) printable SiBCN(O) ceramic precursor (UV-hPBSZ), derived through a straightforward aminolysis approach. The unique hyperbranched molecular structure of UV-hPBSZ leads to remarkable UV curing efficiency, excellent printability, satisfied ceramic yield, and consistent shrinkage ratio. UV-hPBSZ also exhibits superior resistance against cracking and collapse during the polymer-to-ceramic process, thus enabling the fabrication of intricate SiBCN(O) ceramic structures. Upon pyrolysis at 1200 °C, the resulting SiBCN(O) ceramic demonstrates outstanding electromagnetic wave (EMW) absorption performance, achieving full coverage in the X band (RLmin = -36.68 dB). To showcase the design flexibility, a distinctive metastructure is proposed and successfully fabricated using DLP printing technique. This SiBCN(O) metastructure absorber enables impressive EMW absorption in the Ku band (94.6 % coverage), attributed to surface resonance effects and multiple internal reflections. Moreover, SiBCN(O) ceramics exhibit excellent high-temperature stability, with less than a 1.63 % total mass change from room temperature to 1400 °C. UV-hPBSZ offers a simple but versatile way to control dielectric properties, which opens up new possibilities for multifunctional integrated EMW absorbers suitable for both ambient and high-temperature conditions.

Co-manipulation of defects and porosity for enhancing the electrical insulation, microwave absorbing/shielding, and thermal properties of filter-paper-derived 2D interlinked carbon fiber networks

To develop light-weight polymer-based multifunctional materials with outstanding electromagnetic wave absorbing/shielding properties and high thermal conductivity, 2D interlinked carbon fiber networks (2D ICFNs) were synthesized via direct pyrolysis of filter papers at 600–900 °C. The pyrolysis temperature (Tp) was controlled to modulate the porosity, defects, and the resulting properties of 2D ICFNs. Owing to the co-manipulation of defects and porosity, the 2D ICFNs formed under Tp = 900 °C exhibit a larger EABWmax/d (3.57 GHz/mm) and stronger absorption (−44.66 dB) at a lower load (15%) compared to most other carbon fiber (CF)-based materials. Their shielding effectiveness is beyond 20 dB over 2.0–18.0 GHz with a maximal value of 76.2 dB at 18 GHz, surpassing the minimum requirement (20 dB) for practical applications. Besides, the 2D ICFNs with moderate porosity and high graphitization bear a larger thermal conductivity (2.69–2.93 W/mK) at a lower filling ratio (20 wt%) in comparison to the majority of previously reported materials. This is primarily due to the shortened phonon/electron transfer paths, decreased phonon-interface/-defect scattering, and continuous paths for thermal transmission in the 2D ICFNs. Overall, it is believed that the 2D ICFNs can be one of the most promising multifunctional fillers for EM absorption applications.

Foamed concrete composites: Mn–Zn ferrite/carbon fiber synergy enhances electromagnetic wave absorption performance

In order to achieve multi-functional integration of materials and reduce electromagnetic pollution in the building environment, this paper uses foam concrete as a base, combined with magnetic loss absorbing material Mn–Zn ferrite (MZF) and resistance absorbing material carbon fiber to prepare a composite material with outstanding electromagnetic wave (EMW) absorption performance. The EMW absorption performance and mechanisms of the composites in the 0.2–5 GHz frequency range were studied, and the mechanical properties, hydration products, aperture parameters, and conductivity of the composites were analyzed. The results demonstrate that the magnetic loss of MZF in composites primarily comes from eddy current loss, domain wall resonance loss, and natural resonance loss. The combination of MZF and carbon fiber not only synergizes the electromagnetic loss capability, but also improves the impedance matching of the composite material, significantly enhancing the EMW absorption effect. The minimum reflection loss of the composite material in the tested frequency band is −28.75 dB (2.10 GHz, thickness 10 mm) and the effective absorption bandwidth is 1.46 GHz (2.29–3.75 GHz) at a thickness of 5.8 mm.

Co/C composites generated from biomass exhibit outstanding electromagnetic wave absorption

The development of high-performance electromagnetic wave-absorbent materials from inexpensive biomass feedstock is currently the subject of considerable interest. In this study, we developed Co/C composites with excellent electromagnetic wave absorption properties using a simple carbonization method with mangosteen shells as a precursor. The Co/C composite has a minimum reflection loss value (RLmin) of −61.88 dB and a maximum effective absorption bandwidth of 6.32 GHz. For thicknesses ranging from 1 to 5.5 mm, the effective absorption frequency range could cover the entire C, X, and Ku bands. The magnetic loss produced by Co and the dielectric loss, dipole polarization, interfacial polarization, and multiple reflections of biomass carbon synergies enhance the impedance matching capabilities and microwave absorption performance of the composites. The results demonstrate that the activated mangosteen shell magnetic composite has a wider effective absorption bandwidth and greater absorption intensity. This work provides a good potential method for preparation of magnetic particle/biomass-derived carbon microwave absorbing structural materials.