Efficient Electromagnetic Wave Absorption Research Articles

Multifunctional ultralight magnetic Fe3O4@SiO2/Ti3C2Tx/rGO aerogel with efficient electromagnetic wave absorption and thermal management properties

The rational and effective fabrication of multicomponent materials, coupled with innovative microstructure design, remains a formidable challenge in achieving efficient electromagnetic wave absorption (EMA) behaviors to meet the requirement of rapid advances in electronics. Herein, a three-dimensional (3D) hierarchically porous Fe3O4/SiO2/Ti3C2Tx MXene/rGO (FSMRG) aerogels were obtained via a directional freeze-drying and subsequent thermal reduction strategy. It has been found that with the filling ratio of 5 wt%, the ultralight FSMRG-2 aerogel (7.42 mg cm−3) exhibits optimal EMA performances with a minimum reflection loss (RLmin) of −76.6 dB, and the corresponding maximal effective absorption bandwidth (EAB) is up to 5.36 GHz covering the frequency ranges from 12.48 GHz to 17.84 GHz. The outstanding EMA performances of FSMRG-2 aerogel can be attributed to the synergy effects from the multicomponent interfacial polarization, multiple loss pathways and favorable impedance matching as evidenced with the electromagnetic parameter analysis. In addition, the FSMRG-2 aerogel also displays excellent hydrophobicity and thermal insulation capabilities, rendering them suitable for application in complicated environments characterized by humid and high-temperature conditions. Therefore, this study presents a reliable and facile strategy for the precise construction of lightweight, efficient and multifunctional EMA materials.

Cationic pre-insertion interlayer engineering of manganese dioxide for highly efficient electromagnetic wave absorption

Interlayer engineering of two-dimensional structural materials provides unique advantages for tuning the electromagnetic properties of metal oxides, injecting unlimited energy into the design of advanced two-dimensional metal oxide electromagnetic wave absorbers. In this study, Manganese dioxide intercalated with alkali metal ions was prepared by a simple molten salt method. The pre-intercalation of ions not only enhances the polarization loss at the heterogeneous interface between cations (point sites) and manganese dioxide (face sites) but also alters the energy band structure of manganese oxide and enhances its electrical conductivity, which in turn enhances the conductive loss of the manganese dioxide. Due to the synergistic effect of multiple polarizations and conductive losses, NaMO exhibits superb electromagnetic wave absorption properties and an effective absorption bandwidth of 5.36 GHz at thinner matched thicknesses. In addition, the RCS simulation result further verifies the excellent electromagnetic wave absorption capability of NaMO. Under the positive incidence of electromagnetic waves, the electromagnetic wave reflection intensity of the metal plate coated with NaMO is effectively reduced. Finally, this work establishes a new way to modulate the electromagnetic properties.

Synthesis of flowerlike vanadium diselenide microspheres for efficient electromagnetic wave absorption

The revelation of MoS2 as an efficient electromagnetic wave (EMW) absorbing material has ratcheted up people’s attention to other transition metal dichalcogenides (TMDs). To date, extensive studies have been conducted on the semiconducting VIB-Group TMDs while research into metallic VB-Group TMDs has been relatively rare. In this work, we successfully fabricated VB-Group VSe2 microspheres through a facile one-step hydrothermal method and used them as EMW absorbers. The flowerlike VSe2 microspheres based on VSe2 nanosheets exhibited a minimum reflection loss of 46.58 dB with an effective absorption bandwidth of 4.86 GHz. The influence of material morphology, microstructure, and dielectric properties on the EMW absorption performance was systematically investigated. The hierarchically layered structure promoted dielectric loss and EMW absorption by means of multiple reflection, interfacial polarization and related relaxation, and enhanced attenuation ability. This work not only demonstrates that VSe2 is potentially a high-efficiency single component EMW absorber, but also provides fresh insights into exploration on the EMW loss mechanisms of the metallic TMD-based absorbing materials.

(Zn0.6Ni0.3Cr0.1)1.02(Fe2O4)0.98/biocarbon composite: A broad band and highly efficient electromagnetic wave absorber

The combination of carbon and magnetic materials have drawn extensive attention for microwave absorption. In this study, high-performance microwave absorbing materials are prepared by direct mechanical mixing (Zn0.6Ni0.3Cr0.1)1.02(Fe2O4)0.98 (ZnNiCrFeO) with leaf biocarbon. After mixing with biocarbon, the magnetic materials present decent micro-wave reflection loss. Especially, the minimum reflection loss value of −41.08 dB is achieved. The excellent conductivity of biocarbon, magnetic loss of ZnNiCrFeO, and interface polarization loss (between ZnNiCrFeO and biocarbon) jointly determined the electromagnetic absorbing performance. The appropriate impedance matching as well as the synergetic effect between the biocarbon and ZnNiCrFeO magnetic material are also considered. These achievements light the way to prepare low-cost microwave absorbents with excellent electromagnetic wave absorbing performances, utilizing the leaf as precursors.

Ultrabroad electromagnetic absorbing core-shell SiC@SiO2 nanocomposites derived from in situ oxidation SiC whiskers

The amazing developing electromagnetic technology has brought severe challenges to the military and civilian fields, efficient electromagnetic wave absorption (EWA) materials with high-temperature resistance are urgent needed. In this paper, SiC@SiO2 nanocomposites with unique core-shell structures were successfully prepared using a straightforward method by in situ oxidation SiC whiskers. By regulating the sintering temperature and oxidation time, the microstructures and EWA performance of SiC@SiO2 nanocomposites were explored. The results show that the core-shell SiC@SiO2 nanocomposites obtained after sintering at 1200 ℃ for 0.5 h exhibits the best EWA performance, where the minimum reflection loss (RLmin) of −36.80 dB at the thickness of 2.68 mm and the effective absorption bandwidth (RL<-10 dB, EAB) of 9.85 GHz at a matching thickness of 4.24 mm. Specially, the EAB can reach up 10.98 GHz with the filling content of only 10%, which surpasses most SiC-based absorbers. The ultrabroad absorbing bandwidth can be attributed to that the unique core-shell structures of SiC whiskers with in-situ grown SiO2 layers on the surface provide good impedance matching, multiple reflection and scattering and interface polarization effects. This work provides a new strategy for the design of high temperature resistant absorbing materials.

Construction of 1D heterogeneous PPy@FeCo@PPy nanotubes with broadband and strong electromagnetic wave absorption

Developing nanomaterials with efficient electromagnetic wave absorption to eliminate increasingly serious electromagnetic pollution is of great significance. The peculiar electromagnetic characteristics of one-dimensional dielectric-magnetic heterostructures bring a promising strategy for designing high-efficiency absorber. Herein, a hierarchical PPy@FeCo@PPy nanotube was fabricated through a process of oxidative polymerization and electroless plating. In the product, the FeCo nanoparticles are encapsulate in the middle of the polypyrrole (PPy) dual conductive layers, which facilitates the deep construction of heterointerfaces and simultaneously prevents magnetic agglomeration. Furthermore, the hollow structure and suitable dielectric-magnetic component optimize impedance matching. Profiting from the reasonable structural design and the strong synergistic loss mechanism of dielectric-magnetic, the coaxial multi-shell PPy@FeCo@PPy nanotube exhibits prominent electromagnetic wave absorption performance, with a minimum reflection loss of −50.5 dB and the effective absorption bandwidth of 5.7 GHz at 2.0 mm. This work offers a gentle strategy for preparing ideal microwave absorbers by constructing dielectric-magnetic heterogeneous interfaces.

Polypyrrole/Fe3O4 nanocomposites anchored on graphene toward efficient electromagnetic wave absorption performance

The ternary nanocomposites of polypyrrole/Fe3O4/graphene (PPy/Fe3O4/RGO) have been prepared via a two-step method. PPy/Fe3O4 composites have been initially anchored on GO surface by chemical one-step method following by reducing GO. The electromagnetic wave absorption (EMWA) performance of composites can be tuned by adjusting the amount of pyrrole monomers. The maximum reflection loss of the PPy/Fe3O4/RGO-0.5 (pyrrole:0.5 mL) composite is up to −66.0 dB at 14.88 GHz and the absorption bandwidths exceeding −10 dB were 5.76 GHz with absorber thickness of 2.5 mm. The investigation of the electromagnetic absorb-ability reveals that PPy/Fe3O4/RGO exhibits enhanced electromagnetic absorption properties compared to Fe3O4/RGO, which is mainly ascribed to the improved impedance matching, the enhanced interfacial effects and geometric effect. Furthermore, this strategy expands the scope of the electromagnetic wave absorption materials. It confirms that modification of graphene with PPy and Fe3O4 makes the ternary nanocomposites have a promising future in electromagnetic wave absorption materials.

Structural design in reduced graphene oxide (RGO) metacomposites for enhanced microwave absorption in wide temperature spectrum

High-temperature microwave absorbing materials (MAMs) and structures are increasingly appealing due to their critical role in stealth applications under harsh environments. However, the impedance mismatch caused by increased conduction loss often leads to a significant decline in electromagnetic wave absorption (EMWA) performance at elevated temperatures, which severely restricts their practical application. In this study, we propose a novel approach for efficient electromagnetic wave absorption across a wide temperature range using reduced graphene oxide (RGO)/epoxy resin (EP) metacomposites that integrate both electromagnetic parameters and metamaterial design concepts. Due to the discrete distribution of the units, electromagnetic waves can more easily penetrate the interior of materials, thereby exhibiting stable microwave absorption (MA) performance and impedance-matching characteristics suitable across a wide temperature range. Consequently, exceptional MA properties can be achieved within the temperature range from 298 to 473 K. Furthermore, by carefully controlling the structural parameters in RGO metacomposites, both the resonant frequency and effective absorption bandwidth (EAB) can be optimized based on precise manipulation of equivalent electromagnetic parameters. This study not only provides an effective approach for the rational design of MA performance but also offers novel insights into achieving super metamaterials with outstanding performance across a wide temperature spectrum.

Facile design and permittivity regulation of porous carbon and magnetic particles based composite nanofibers towards highly efficient electromagnetic wave absorption

Two kinds of porous carbon and magnetic particles-based composite nanofibers (PCNTF-CoFe and PCNTF-NiFe) were synthesized for electromagnetic wave (EMW) absorption. Magnetic particles were used as the catalyst to increase the crystallinity of carbon and the corresponding dielectric loss ability, while porous structure was designed to improve the impedance matching. According to the results, the dielectric loss abilities of PCNTF-CoFe and PCNTF-NiFe are enhanced without significant degradation in their impedance matching condition. Therefore, through the polarization and conduction-induced dielectric loss together with the natural and exchange resonance-induced magnetic loss, the incident EMW can be attenuated rapidly inside PCNTF-CoFe and PCNTF-NiFe. PCNTF-CoFe shows a minimum reflection loss (RLmin) of −54.6 dB and effective band width (RL≤-10 dB, EABW) of 6.0 GHz at 2.0 mm, while PCNTF-NiFe shows RLmin of −33.4 dB and EABW of 5.7 GHz at 1.7 mm. Consequently, PCNTF-CoFe and PCNTF-NiFe can be promising candidates for application in EMW absorption.

Hierarchical heterostructure Ni2P hollow carbon spheres derived from MOFs for efficient electromagnetic wave absorption

In this study, a hierarchical heterogeneous structure of Ni2P hollow carbon spheres (Ni2P-HCS) was synthesized through a two-step process involving carbonization and phosphorization of Ni-metal organic framework (Ni-MOF) precursors. During the construction of the Ni2P/C nanostructure, heterointerface recombination and secondary graphitization were observed, which contribute to the modulation of interface polarization. Structural analysis revealed that the Ni2P/C nanoparticles are uniformly dispersed, forming stable porous structured microspheres, thereby leveraging dielectric and magnetic losses. The combination of Ni2P with metal-organic frameworks (MOFs) can optimize impedance matching, enhance effective absorption bandwidth, and consequently improve electromagnetic wave absorption performance. The results show that Ni2P-HCS (Ni2P-HCS700) exhibited superior electromagnetic wave (EMW) absorption characteristics when the carbonization temperature is 700 ℃. It achieves a maximum reflection loss (RL) of −46.7 dB at a thickness of 2.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz at 1.71 mm thickness, almost covering the Ku-band (13.3 GHz−18 GHz). Radar cross-section (RCS) simulations utilizing CST indicated an optimal RCS reduction value of 41 dB m² at theta=0° for Ni2P-HCS700. This work introduces a universal approach to designing high-performance lightweight absorbers derived from MOFs, incorporating transition metal phosphides to form composites for impedance matching control.

Multi-electron transfer mechanism and band structures of CNTs in MOF-derived CNTs/Co hybrids for enhanced electromagnetic wave absorption property

Metal-organic framework (MOF)-derived magnetic metal/carbon nanocomposites have received widespread attention for electromagnetic wave (EMW) absorption. The present study introduces a novel approach to MOF composite material design by constructing composites modified with carbon nanotubes (CNTs) and magnetic Co nanoparticles. The carbon confinement effect in CNT/Co not only regulates the electronic structure of Co-C bonds, but also maintains the redox cycle of Co0/2→Co3+→Co0/2+, improving electronic activity and exhibiting synergistic integration characteristics of efficient electromagnetic wave absorption. Particularly, the maximum reflection loss (RLmin) of CNTs/Co-900 reached −52.7 dB at 4.67 GHz in the case of an absorber thickness of 1.6 mm. The excellent microwave absorption performance may be attributed to the interwoven structure formed by novel ZIF-67, CNTs, and Co metal nanoparticles and the double loss of magnetic Co and dielectric CNTs. In addition, the band gap of CNTs was calculated to be Eg = 0.27 eV by the semi-empirical tight-binding method with DFTB+. It is confirmed that CNTs have high electron migration ability, which is beneficial to conductive loss. It is confirmed that CNTs have high electron migration ability, which is beneficial to conductive loss. This study provides a novel strategy for the development of metal-organic framework-based magnetic particles/carbon nanocomposites for electromagnetic wave absorption.

Zn/Co/C hollow nanocube for electromagnetic wave absorption

Hollow zinc/cobalt/carbon(Zn/Co/C) composites are obtained through encapsulation and etching of tannins and carbonization processes. When the carbonization temperature is 600 °C, Zn/Co/C shows efficient electromagnetic (EM) wave absorption properties. The minimum reflection loss (RL) reaches −57.6 dB at 9.4 GHz with a thickness of 3.5 mm. When the thickness is 2.6 mm, the maximum effective absorption bandwidth (EAB) reaches 6.75 GHz (10.54–17.29 GHz). The excellent performance is attributed to the abundant dielectric loss and magnetic loss effects. The results have positive significance for the research of hollow carbon-based composite absorbers.

Construction of two-dimensional thick sheet-like carbide and Co nanocrystals heterostructure toward efficient electromagnetic wave absorption

Deeply studied the electromagnetic wave absorption (EWA) mechanism of Mo2C heterostructure is crucial for realizing the application of Mo2C-based materials in new multifunctional integrated microwave absorbing coatings. In order to exclude the influence of special three-dimensional morphology (spherical, hollow, etc) on EWA performance, we designed the two-dimensional (2D) thick sheet-like Mo2C/Co@NC heterostructure that composed of molybdenum carbide (Mo2C), cobalt (Co) nanoparticles and nitrogen-doped carbon (NC), derived from the MoO42− substituted 2D sheet-like Co zeolite imidazolate frameworks (Mo/Co BIFs). The Mo2C/Co@NC has better EWA performance than Co@NC and Mo2C@NC. In the thickness range of 2∼4 mm, the effective absorption bandwidth can cover up to 10.5 GHz, and the strongest absorption can reach −48 dB. Behind the excellent EWA performance, multiple polarization relaxation and enhanced interface polarization are acting together. Moreover, the structure and interface effects of Mo2C/Co heterojunction are also revealed by DFT calculation. This work provides a workable methodology for manipulating the heterogeneous interface of MOFs-derived Mo2C based material and understanding the EWA mechanism of Mo2C-based heterostructure.

Short carbon nanorod-grafted N-doped carbon nanocages derived from LDH/MOFs for efficient electromagnetic wave absorption

The systematic design of morphology and structure plays a significant role in enhancing the physicochemical properties of functional materials. In this work, short carbon nanorod-grafted magnetic N-doped carbon nanocage (FeCoNi@NC) was prepared using FeCoNi layered double hydroxide (LDH)/metal organic frameworks (MOFs) as precursor. Herein, a multi-level hollow nanocage was synthesized by hydrothermal method, in which nanorods were formed on the surface of the hierarchical structure, and after annealing, an N-doped hollow nanocage with short carbon nanorod-grafted was formed. Due to its unique hollow and hierarchical interfaces, the optimal FeCoNi@NC exhibits highly efficient electromagnetic wave absorption (EWA). At 14.32 GHz, the minimum reflection loss (RLmin) reach −54.4 dB, while the effective absorption bandwidth (EAB) is over a wide range of 5.28 GHz, corresponding to a thickness of 1.5 mm. The outstanding ability to absorb electromagnetic waves is due to the hierarchical and hollow characteristics, which increase dielectric and conductive losses, while also optimizing impedance matching. The study presents a highly effective approach to fabricate hierarchical and hollow nanostructures with short nanorods, aiming to enhance the efficiency of EWA.

Radio-Absorbing Magnetic Polymer Composites Based on Spinel Ferrites: A Review.

Ferrite-containing polymer composites are of great interest for the development of radar-absorbing and -shielding materials (RAMs and RSMs). The main objective of RAM and RSM development is to achieve a combination of efficient electromagnetic wave (EMW) absorption methods with advantageous technological and mechanical properties as well as acceptable weight and dimensions in the final product. This work deals with composite RAMs and RSMs containing spinel-structured ferrites. These materials are chosen since they can act as efficient RAMs in the form of ceramic plates and as fillers for radar-absorbing polymer composites (RAC) for electromagnetic radiation (EMR). Combining ferrites with conducting fillers can broaden the working frequency range of composite RAMs due to the activation of various absorption mechanisms. Ferrite-containing composites are the most efficient materials that can be used as the working media of RAMs and RSMs due to a combination of excellent dielectric and magnetic properties of ferrites. This work contains a brief review of the main theoretical standpoints on EMR interaction with materials, a comparison between the radar absorption properties of ferrites and ferrite-polymer composites and analysis of some phenomenological aspects of the radar absorption mechanisms in those composites.

Design of morphology-controlled cobalt-based spinel oxides for efficient X-band microwave absorption

The cobalt-based spinel structure oxides with synergistic effect of magnetic loss and dielectric loss have important applications in electromagnetic wave absorption. And the excess 0.5 oxygen atoms in MnCo2O4.5 provide more vacancies than traditional MnCo2O4 spinel structure and improve the electrical conductivity. In the current study, MnCo2O4.5 microsphere clusters, MnCo2O4.5 microcubic spheres and MnCo2O4.5 flowery spheres were prepared by solvothermal method and annealing process. Among the final samples with different morphologies, MnCo2O4.5 microcubic spheres showed outstanding microwave absorption capabilities, with a minimum reflection loss (RLmin) of -51.52 dB at 2.2 mm. When the thickness was further increased to 2.3 mm, the effective absorption bandwidth could be as wide as 5.36 GHz, covering most of the X-band. The excellent absorption performance of electromagnetic waves is related to the modulability of the complex dielectric parameters, the optimization of impedance matching, and the enhancement of the polarization relaxation process through the improvement of the morphologies. This work provides guidance and support for refining the electromagnetic wave absorption potential of cobalt-based spinel oxides and for designing highly efficient electromagnetic wave absorbers in the X-band.

Biomass derived PANI/BPC composite with enhanced polarization loss for efficient electromagnetic wave absorption

Based on the strategies of heterogeneous interface construction and impedance matching optimization, the polyaniline/biomass derived porous carbon (PANI/BPC) has been synthesized. The attachment of PANI on the surface of BPC prompts a relatively amount of heterogeneous interface endowing sufficient interfacial polarization loss. Meanwhile, the coralline-like PANI acts as bridges on the surface of BPC to construct complex conductive networks enhancing conduction loss and multi-reflections & scattering. The balances between conduction loss and polarization loss, impedance matching and attenuation capability have been established. Thanks to the synergistic effect of strong dielectric loss and optimized impedance matching, the PANI/BPC composite achieves the optimal absorption capacity with the minimum reflection loss (RL) of -40.89 dB at 2.6 mm and the effective absorption bandwidth (EAB) of 4.24 GHz at 2.1 mm. This satisfactory result may provide a new approach for the effective development and utilization of biomass derived porous carbon as absorbing materials.

Facile preparation of ZIF-8/ZIF-67-derived biomass carbon composites for highly efficient electromagnetic wave absorption

Biomass absorbing materials have received increasing attention for electromagnetic wave (EMW) absorption field absorbing materials due to its low density and high dielectric loss. However, the biomass EMW absorbing materials often suffer from the insufficient magnetic loss and impedance matching. In this work, a facile ZIF-8/ZIF-67-derived biomass composites (CoZnO@BPC) was prepared for high-performance EMW absorption based on multi-component micro, nano structures metal particles and xanthoce sorbifolia bunge shells-derived biomass porous carbon (BPC). The dielectric loss and/or magnetic loss abilities of CoZnO@BPC composites were adjusted by changing the mass ratio of Zn2+ to Co2+ ions. Under the filled amount of 20 wt%, CoZnO@BPC exhibited excellent EMW absorption with the minimum reflection loss (RL) at 15.84 GHz is -50.2 dB, and the matching thickness is only 1.7 mm. By adjusting the ZIFs mass ratio, the effective absorption bandwidth (EAB) can be up to 5.92 GHz (from 12.08 GHz to 18 GHz), and the matching thickness is only 1.9 mm. The results provide a new insight for the economical and efficient preparation of lightweight and advanced microwave absorbing materials.

Carbon microspheres/carbon sheets as efficient electromagnetic wave absorbers

To address the issue of weak absorption intensity and narrow frequency band in pure dielectric electromagnetic wave (EMW) absorbing materials, this study adopts a simple method to successfully prepare a pure dielectric EMW absorption material by modifying acrylonitrile–methylmethacrylate copolymer carbon microspheres (co-AN-MMA@CS) with capsaicin-like 3,5-dimethylphenol derivative (DMPD). The introduction of DMPD into the carbon microspheres increases the heteroatoms (N, O) in the carbon material, thus resulting in functional groups (-C-N, –NO, and C–O) that enable energy loss through dipole polarization. Additionally, the special morphology of carbon microspheres attached or embedded in carbon sheets derived from DMPD increases the inhomogeneous interfaces, thereby increasing the interface polarization relaxation and further attenuating EMWs. The resulting carbon material with the optimal structure (denoted as CNO-2) exhibits superior EMW absorption properties. At a thickness of 2.50 mm, the minimum reflection loss (RLmin) reaches −63.10 dB at 13.14 GHz, whereas the maximum effective absorption bandwidth (EABmax) reaches 6.81 GHz (8.95–15.76 GHz). CNO-2 has excellent EMW absorption capabilities due to the controllable complex dielectric constant and multiple attenuation mechanisms, including interfacial polarization, dipole polarization, and conduction loss. The CNO absorbers prepared in this study can be used as efficient microwave absorbers for electromagnetic protection applications.

Synthesis of Co@N-doped carbon with yolk–shell heterostructures for efficient electromagnetic wave absorption

Regulating the composition and microstructure of nanomaterials is a major challenge in the development of high-performance materials for electromagnetic wave (EMW) absorption. This paper introduces a new lightweight EMW-absorbing material Co@N/C with a yolk–shell structure and compositions of ferromagnetic metal and carbon materials. The minimum reflection loss (RLmin) of the as-designed Co@N/C nanospheres with a filler loading of 25 wt% reaches −67.68 dB and the effective absorption bandwidth of a 1.9 mm thickness is 5.3 GHz. The exceptional absorption performance of the EMW absorption is primarily achieved through the synergistic effect between the Co–carbonaceous material and the yolk–shell structure, which optimizes the impedance matching. The polarization loss, conductivity loss, magnetic loss, and multiple scattering mainly contribute to the excellent EMW-absorption ability of the materials. The proposed method for regulating the structure and morphology of Co@N/C can efficiently construct high-performance EMW absorbers.