High-performance Electromagnetic Wave Absorption Research Articles

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.

Facile Recycling of Waste Biomass for Preparation of Hierarchical Porous Carbon with High-Performance Electromagnetic Wave Absorption.

Hierarchical-porous-structured materials have been widely used in the field of electromagnetic wave (EMW) absorption, playing a critical role in minimizing EMW interference and pollution. High-quality EMW absorbers, characterized by a lower thickness, lighter weight, wider absorption band, and stronger absorption capacity, have been instrumental in reducing damage and preventing malfunctions in the automotive and aviation industries. The utilization of discarded nut shells through recycling can not only alleviate environmental problems but relieve resource constraints. Herein, a facile method for the preparation of hierarchical porous biomass carbon derived from abandoned Xanthoceras Sorbifolium Bunge Shell (XSS) biomass was developed for high-performance EMW absorption. The porous structures of XSS biochar were studied by using different levels of the K2CO3 activator and simple carbonization. The effect of K2CO3 on the EMW parameters, including the complex permittivity, complex permeability, polarization relaxation, and impedance matching, was analyzed. The best EMW absorption performance of the XSS biochar was observed at a mass ratio of activator-to-biomass of 2:1. A minimum reflection loss (RLmin) of -38.9 dB was achieved at 9.12 GHz, and a maximum effective absorption bandwidth (EABmax) of up to 3.28 GHz (14.72~18.0 GHz) could be obtained at a 1.8 mm thickness. These results demonstrated that hierarchical porous XSS carbon was prepared successfully. Simultaneously, the prepared XSS biochar was confirmed as a potential and powerfully attractive EMW-absorbing material. The proposal also provided a simple strategy for the development of a green, low-cost, and sustainable biochar as a lightweight high-performance absorbing material.

Heterogeneous interface engineering of SiBCN/Ni fibers extends enhanced electromagnetic wave absorption properties

Faced with severe electromagnetic wave (EMW) pollution, the development of high-performance EMW absorbers remains a formidable challenge. In this study, SiBCN/Ni fibers containing uniformly dispersed Ni2Si nanoparticles were synthesized by electrospinning method with polymer-derived ceramics method, and their electromagnetic properties were evaluated. The low permeability threshold of the fibers ensures sufficient conduction loss effect. The in situ grown Ni2Si nanoparticles provide a magnetically coupled network, which is more conducive to obtaining excellent impedance matching. Furthermore, the presence of β-SiC, SiO2, and Si2N2O generates numerous heterogeneous interfaces (e.g., C-SiC and C-Ni2Si), leading to enhanced interfacial polarization through the accumulation of charges. As a result, the prepared SiBCN/Ni fibers exhibit impressive EMW absorption properties. At a Ni content of 1 wt%, the effective absorption band (EAB) is 4.32 GHz (13.68–18 GHz). At a Ni content of 1.5 wt%, the minimum reflection loss (RLmin) is −52.98 dB, and the sample has excellent radar scattering capabilities, which is verified by CST Microwave Studio simulations. Therefore, SiBCN/Ni fibers are promising as excellent EMW absorbing materials in practical applications.

Rational design of SiBCN ceramics with excellent attenuation to strong electromagnetic-wave-absorbing properties at low frequency

To achieve strong electromagnetic wave absorbing properties, it is important to have good impedance matching, moderate electrical conductivity, and high polarization loss, particularly at low frequency. However, meeting these requirements for polymer-derived ceramics remains challenging. This paper proposes a simple approach to addressing this challenge by adjusting the crystallinity and defects of SiBCN ceramics. The addition of Sm as a catalyst and tailored heating temperatures were used to create SiBCN ceramics with adjustable crystallinities and defective nanograins. The controlled crystallinity provided good impedance matching, while the tailored defective nanograins offered high polarization loss. The combination of these factors results in high-performance electromagnetic wave absorption, with the SiBCN ceramics achieving a minimum reflection loss of −59.13 dB at 3.6 GHz and an effective attenuation bandwidth of 6.87 GHz with a thickness of 2.22 mm. This study provides an effective strategy for the design and fabrication of strong EMW absorbing materials.

Rational construction of ZnFe2O4 decorated hollow carbon cloth towards effective electromagnetic wave absorption

As typical magnetic materials, ferrites and their composites play dominant roles in the design of high-performance electromagnetic wave (EW) absorber. Solvent thermal method is the most popular route for synthesizing ferrites, while systematical comparison research about the influence of reaction solvents of solvent thermal process on ferrite based material's EW absorption performance has rarely been carried out. Thus in this work, we adopted cotton fabric as raw material, and synthesized two kinds of zinc ferrite decorated hollow carbon cloth (CC@ZnFe2O4) composites through solvent thermal reaction where deionized water and ethylene glycol was adopted as reaction solvents, respectively. After comprehensive and detailed comparison of the structures and performances of these two ferrite composites, the CC@ZnFe2O4 synthesized in deionized water phase possesses an ideal optimal absorption efficiency for EW, that is the minimum reflection loss (RL min) of −46 dB, while the effective absorption bandwidth of CC@ZnFe2O4 composites synthesized in ethylene glycol phase is wider (4.9 GHz). The synergistic effect of impedance matching, interface polarization, magnetic resonance, and multiple reflections co-determined the ideal EW absorption performances of these two samples. The research can not only provide new guidance for the secondary utilization of waste textiles, but also become an important reference for the preparation of ferrite based high-performance EW absorbers through solvent thermal method.

In Situ Loading of Ni3ZnC0.7 Nanoparticles with Carbon Nanotubes to 3D Melamine Sponge Derived Hollow Carbon Skeleton toward Superior Microwave Absorption and Thermal Resistance.

The simple and low-cost construction of a 3D network structure is an ideal way to prepare high-performance electromagnetic wave (EMW) absorption materials. Herein, a series of carbon skeleton/carbon nanotubes/Ni3ZnC0.7 composites (CS/CNTs/Ni3ZnC0.7) are successfully prepared by in situ growth of Ni3ZnC0.7 and CNTs on 3D melamine sponge carbon. With the increase ofprecursor, Ni3ZnC0.7 nanoparticles nucleate and catalyze the generation of CNTs on the surface of the carbon skeleton. The minimum reflection loss (RL) value of the S60min composite (loading time of 60 min) reaches -86.6dB at 1.6mm and effective absorption bandwidth (EAB, RL≤-10dB) is up to 9.3GHz (8.7-18GHz). The 3D network sponge carbon with layered micro/nanostructure and hollow skeleton promotes multiple reflection and absorption mechanisms of incident EMW. The N-doping and defects can be equivalent to an electric dipole, providing dipole polarization to increase dielectric relaxation. The uniform Ni3ZnC0.7 nanoparticles and CNTs play a key role in dissipating electromagnetic energy, blocking heat transfer, and enhancing the mechanical properties of the skeleton. Fortunately, the composite displays a quite low thermal conductivity of 0.09075Wm·K-1 and good flexibility, which can provide insulation and quickly recover to its original state after being stressed.

Synthesis of porous carbon-encapsulated MoxC/Co based on NaCl template and ZIF-67 towards enhancing electromagnetic wave absorption

Although molybdenum carbide (MoxC) has emerged as an effective absorber of electromagnetic (EM) waves, its practical application is hindered by impedance mismatch and single loss mechanism. Herein, we developed a one-step method for creating NaCl template precursors assembled with ZIF-67 to produce porous multiple components of MoxC composites. The MoxC-Co/C composites exhibit a minimum reflection loss (RLmin) of −59.69 dB with a bandwidth of 3.12 GHz at a thickness of 1.50 mm. The RLmin reaches −71.39 dB with a bandwidth of 4.08 GHz at a thickness of 2.09 mm. The flower-like MoxC-Co/C composites are capable of improving impedance matching and offering multiple loss mechanisms such as interfacial polarization, dipolar polarization, conductive loss and magnetic loss, resulting in enhanced EM wave absorption. Thus, our work featured a simple strategy to provide a unique insight into fabricating high-performance EM wave absorbers on molybdenum carbon basis.

Multifunctional graphene/Ti3C2Tx MXene aerogel inlaid with Ni@TiO2 core-shell microspheres for high-efficiency electromagnetic wave absorption and thermal insulation

The demand for high-performance electromagnetic wave absorbing (EMA) materials featured with strong attenuation ability, extended absorption bandwidth and ultralight property is imperative yet remains challenging. Herein, a three-dimensional hierarchically porous reduced graphene oxide (rGO)/Ti3C2Tx MXene aerogel embedded with Ni@TiO2 core–shell microspheres was prepared via directional freeze-drying followed by a mild annealing process. The divergence in structure and multicomponent dielectric/magnetic features bring about optimized impedance matching characteristic, multiple polarization and loss pathways, collectively contributing to the excellent absorption performance. As a result, the Ni@TiO2/MXene/rGO (NTMRG-2) aerogel exhibits optimized EMA capability with a maximal effective absorption bandwidth (EABmax) of 6.48 GHz at a lower loading level of 5 wt% in the supporting matrix, covering the whole Ku band. Additionally, it achieves a minimum reflection loss (RLmin) of −71.4 dB with a matching thickness of 2.04 mm. Moreover, the aerogel also exhibits an ultra-light density of 5.58 mg cm−3, superior thermal insulation capacity (close to air) and hydrophobicity, underscoring its potential for multiple applications in various scenarios.

Material extrusion 3D printing of large-scale SiC honeycomb metastructure for ultra-broadband and high temperature electromagnetic wave absorption

Electromagnetic (EM) wave absorbing materials have been widely used in various equipment to reduce the interference caused by EM waves. However, current EM wave absorbing materials are limited by narrow absorption bandwidth under high temperatures due to a lack of structural design. Herein, SiC ceramic and large-scale SiC honeycomb metastructure were monolithically fabricated by material extrusion 3D printing. The real permittivity and imaginary permittivity of as-obtained SiC ceramic approached 10 and 2.3 within the frequency of 2–18 GHz. After optimized structure design, the as-obtained SiC honeycomb metastructure exhibited broadband EM performance of −10 dB effective bandwidth from 4.85 to 39.49 GHz (34.64 GHz) when the incident angle was 60° at room temperature. Moreover, the as-obtained SiC honeycomb structure had a stable broadband −10 dB effective bandwidth of above 35 GHz when the incident angle is 60° even after in-situ 1000 °C and ex-situ 1600 °C erosion in the air atmosphere. Broadband EM wave absorption under oblique incident wave was also achieved from 30° to 60° both in transverse electric (TE) polarization and transverse magnetic (TM) polarization. This novel strategy unravels the potential of additive manufacturing of high-performance EM wave absorbers for high temperature environment applications.

High-performance electromagnetic wave absorption by two-dimensional mesoporous monolayer Ti3C2Tx MXene

Transition metal carbide MXene, with its unique chemical composition, structure and sizeable particular surface area, is widely applied in wave absorption. However, the high conductivity of MXene resulted in an impedance mismatch that prevented electromagnetic waves from entering the material to achieve dissipation, and thus, tuning the intrinsic properties of pure MXene to obtain excellent electromagnetic wave absorption is still a challenge. Here, we strengthen the absorption of electromagnetic waves by generating titanium vacancies through hydrogen peroxide etching and thus forming micro-sized wrinkles with porous MXene. Porous MXene possesses an excellent microstructure and surface state, abundant porous defects, and moderate electrical conductivity, allowing it to achieve well-matched impedance, dipole polarization, and conduction loss, thus inheriting excellent electromagnetic wave absorption (EWA) properties. Therefore, the porous MXene achieves a strong absorption of − 63.31 dB and an adequate absorption bandwidth (EAB) of 6.88 GHz at a matched thickness of 2.39 mm with a fill ratio of 6 wt%.

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.

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.

High-performance electromagnetic wave absorbers based on hierarchically porous (Zn1/2Ni1/2)Co2O4 spinel clusters

The development of lightweight electromagnetic wave absorbers with strong absorption performance, and broad absorption bands has garnered significant attention toward electromagnetic protection. In this study, 3D hierarchically porous (Zn1/2Ni1/2)Co2O4 spinel clusters were synthesized via a straightforward hydrothermal reaction followed by calcination. Notably, the (Zn1/2Ni1/2)Co2O4 spinel calcined at 500 ℃, the hierarchically porous (Zn1/2Ni1/2)Co2O4 spinel clusters achieved the minimum reflection loss value and effective absorption band of −66.6 dB and 6.45 GHz at a matching thickness of 2.47 mm and 2.35 mm, respectively. These outcomes were due to the synergistic effects induced by dielectric loss, magnetic loss, and the unique hierarchical porous structure of the prepared spinel. Our findings will promote the development of electromagnetic protection technologies and inspire the design and fabrication of high-performance electromagnetic wave absorbing materials.

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.

Synergistic effect of nickel selenide‑carbon composites for efficient broadband electromagnetic wave absorption

Novel NiSe2-based composites loaded with carbon nanotubes (CNTs) and graphene (GNs), respectively, were successfully synthesized via a facile hydrothermal reaction, aiming to enhance the electromagnetic wave (EMW) absorption performance. Microstructure, morphology, dielectric properties and EMW absorption performance of as-prepared NiSe2/CNTs and NiSe2/GNs composites were explored. Results showed that both NiSe2/CNTs and NiSe2/GNs composites exhibited improvement in EMW absorption compared to pure NiSe2, especially NiSe2/GNs showed the best EMW absorption performance. NiSe2/GNs composites demonstrated an exceptional minimum reflection loss (RLmin) of −52.10 dB at a thin thickness of merely 1.71 mm, accompanied by a wide effective absorption bandwidth (EAB) of 4.1 GHz. However, the EMW absorbing performance of NiSe2/CNTs composites was slightly lower than that of NiSe2/GNs composites, showing an RLmin of −45.10 dB and an EAB of 3.76 GHz at a thin thickness of 1.60 mm. Such significantly enhanced absorption capability of NiSe2/GNs composites can be attributed to the synergistic interplay of desirable impedance matching and efficient attenuation ability. These findings highlight the potential of NiSe2-based composites loading with carbon conductive fillers as highly promising contenders for high-performance EMW absorption materials.

Surface modification by CO2 plasma boosting core shells structural Fe/Fe3C/FeN @ graphite carbon nanoparticles toward high performance microwave absorber

The surface modification of three-dimensional (3D) materials is an efficient method for adjusting their interfacial defect concentration, electronic conductivity and content of functional groups with extensive applications in catalysis, electrode materials and bioengineering. In this work, a multiphase iron nanocrystals consisting of Fe3C, Fe and FeN nanoparticles encapsulated in hierarchical structure of graphite carbon (denoted as Fe/Fe3C/FeN@GC) is synthesized for the first time by a novel high temperature plasma method. Meanwhile, more defects and functional groups are introduced by surface modification of graphite carbon layer of Fe/Fe3C/FeN@GC with controllable CO2 (low temperature) plasma. Benefiting from the advantages of multiple heterogenous interface and the abundant interfacial polarization relaxation that represent strong electromagnetic (EM) wave dissipation as well as an applicable impedance matching, the optimized Fe/Fe3C/FeN@GC demonstrate superior microwave absorption (MA) properties. The minimum reflection loss (RL) achieves −54.4 dB (more than 99.9% MA) at 17.6 GHz with a thin thickness of 1.8 mm, and the maximum effective absorption bandwidth (EAB, RL < −10 dB) is up to 6.2 GHz (11.8–18.0 GHz) at 2.0 mm. The above results reveal that the optimized Fe/Fe3C/FeN@GC composites with strong absorption, broad EAB, light mass (only filling content of 30 wt%) and ultrathin thickness are prospective candidate for high performance EM wave absorbers.

Synthesis and characterization of high-performance electromagnetic wave absorption of CoS/Co9S8/WS2 composites

Synthesis and characterization of high-performance electromagnetic wave absorption of CoS/Co9S8/WS2 composites

Carbon nanofibers embedded with Fe–Co alloy nanoparticles via electrospinning as lightweight high-performance electromagnetic wave absorbers

Carbon nanofibers embedded with Fe–Co alloy nanoparticles via electrospinning as lightweight high-performance electromagnetic wave absorbers

Fabrication of hollow Ni/NiO/C/MnO2@polypyrrole core-shell structures for high-performance electromagnetic wave absorption

In response to the increasingly serious problem of electromagnetic wave pollution, there is a growing demand for materials capable of absorbing electromagnetic waves. A crucial strategy involves optimizing the microstructure and composition of these materials. In this study, the Ni/NiO/C/MnO2@PPy (NCMP) composites are successfully fabricated through the combination of hydrothermal method, high-temperature calcination process, chemical method and in situ polymerization. Due to the strong synergistic effect of the dielectric and magnetic components, and good impedance match, the NCMP-40 exhibits excellent electromagnetic wave absorption properties, with an optimal reflection loss (RLmin) of −56.23 dB at a thickness of 3.87 mm, and a high effective absorption bandwidth (EAB) of 6.86 GHz (10.68–17.54 GHz) at a thickness of 1.97 mm covering the entire Ku-band part of the X-band. Moreover, the radar cross section (RCS) attenuation is obtained through a simulation procedure. Compared to the sole perfect electrically conductive (PEC) layer, the PEC layer coated with NCMP-40 achieves an RCS value consistently below −10 dB m2 in the range of −60° < θ < 60°, and an RCS value is −22.0 dB m2 at θ = 0°. The prepared NCMP-40 presented herein shows excellent electromagnetic wave absorption performances. And this study provides a new method for the structural design of electromagnetic wave absorption materials.

Regulating the carbon shell structure of hollow cubic carbon for high performance electromagnetic wave absorption

Herein, HCCs absorbers were synthesized by pyrolysis of phenolic resin, which was uniformly spread onto the surface of NaCl crystals. An investigation was undertaken to assess the effect of shell thickness on wave-absorbing capacity by altering the timing of the phenolic resin reaction. The morphology, composition and electromagnetic properties of the samples were also analyzed for different reaction times. Scanning electron microscopy (SEM) findings revealed a progressive increase in shell thickness of the HCCs from 28.728 nm to 92.654 nm, accompanied by a gradual enlargement in sample size. Compared to samples obtained at other reaction times, the sample reacted for 48 h exhibited favorable wave absorption properties attributed to its fitting shell thickness and impedance matching. Specifically, at a load rate of 5 wt% and the thickness of 2.7 mm, the maximum reflection loss reaches −50.5 dB with an effective absorption bandwidth of 6.2 GHz (11.8 GHz–18.0 GHz). Thus by altering the synthesis duration of phenolic resin is possible to effectively adjust the carbon shell morphology, thereby enhancing the capability for electromagnetic wave absorption.