High-performance Electromagnetic Wave Absorption Research Articles

A facile strategy for customizing multifunctional magnetic‑dielectric carbon microflower superstructures deposited with carbon nanotubes

The novel fabrication of multiple components and unique heterostructure can inject infinite vitality into the electromagnetic wave (EMW) attenuation field. Herein, through the self-assembly of polyimide complexes and catalytic chemical vapor deposition, porous carbon microflowers were synthesized accompanied by carbon nanotubes (CNTs). By regulating the metal ions, the composition and structure of the as-obtained hybrids are modified correspondingly, and thus the adjustable thermal management and EMW absorption capabilities are obtained. In detail, the rich pores and huge specific surface area endow the hierarchical structures with distinguished thermal insulation ability (λ<0.07). The carbon framework and CNTs are beneficial for consuming EMWs via conductive loss and defect polarization loss while reducing the filling ratio and thickness. The doped heteroatoms and abundant heterointerfaces generate ample dipole polarization and interface polarization losses (supported by DFT calculation). The metal nanoparticles uniformly embedded in the carbon framework offer optimized impedance matching, proper defect polarization, and suitable magnetic loss. Accordingly, the synergy of magnetic-dielectric balance and flower-like superstructure enables FNCFN2 and NNCFN2 to accomplish remarkable microwave absorbing capacity with thin thickness (14 wt.%). Therefore, respectable specific reflection loss and specific effective absorption bandwidth are acquired (215.39 dB mm–1 and 22.10 GHz mm–1, 257.23 dB mm–1 and 22.12 GHz mm–1 respectively), superior to those of certain renowned carbon-based absorbers. The simulation results of electric field intensity distributions, power loss density, and radar cross section reduction (maximum value of 36.02 dBm2) also verify the prominent radar stealth capability. Moreover, the customizable approach can be applied to other metals to obtain fulfilling behaviors. Henceforth, this work provides profound insights into the relationship between structure and performance, and proposes an efficient path for mass-producing multifunctional and high-performance EMW absorbers with excellent thermal properties.

Interfacical polarization dominant rGO aerogel decorated with molybdenum sulfide towards lightweight and high-performance electromagnetic wave absorber

Lightweight reduced graphene oxide aerogel (rGO) has obtained enormous attention as microwave absorber due to anisotropic characteristics in their structure and electromagnetic parameters. However, the controllable preparation of reduced graphene oxide (rGO) aerogels with tailored multidimensional structure with broadened effective absorption bandwidth is a thorny difficulty. In this paper, rGO aerogel decorated with molybdenum sulfide (rGO/MoS2) with three-dimensional (3D) layered porous structure were synthesized by a two-step hydrothermal method. The unique three-dimensional layered porous structure of graphene aerogel not only effectively avoids the stacking of graphene flake layers, but also provides space for the loading of MoS2 nanosheets. The introduction of MoS2 nanosheets compensates for the imbalance of impedance matching caused by graphene due to the excessive conductivity, and the folded MoS2 nanosheets are uniformly loaded on the graphene lamellae, which is conducive to generate multiple reflections and scattering of electromagnetic waves. Besides, the construction of heterogeneous interfaces strengthens the interfacial polarizability of the composites. As a result, excellent electromagnetic wave attenuation properties were obtained for rGO/MoS2, and the effective absorption bandwidth (EAB) reached 6.56 GHz at 2.1 mm. In addition, the radar cross section (RCS) simulation results further demonstrate the dissipation capability of the composite in practical application scenarios. This paper provides a new idea for the design of lightweight EM wave absorbing materials with broad absorption bandwidth.

CO2 plasma inducing steel-slag with active sites for efficient growth of carbon nanotubes for the high-performance microwave absorption

As a solid waste generated in the metallurgical process, the highly efficient catalysis of steel-slag for carbon nanotube (CNT) growth remains a huge challenge. Herein, a CO2 plasma-inducing approach for modifying the steel-slag catalyst with rich active sites was developed for CNT growth in the chemical vapor deposition (CVD) process. Furthermore, the high-energy CO2 plasma refines the particles on the steel-slag surface, reducing the particle size on the surface of steel-slag effectively increasing the active sites of the catalyst. In addition, the thermal effect generated by the gas molecule ionization process under CO2 increases the background temperature of the steel-slag, and the interaction between the oxygen-active substances produced and the iron oxide on the surface of steel-slag undergoes an oxidation reaction upon full contact with high-energy particles, which greatly improves the catalytic efficiency of the steel-slag as a catalyst for CNT, and increases the catalytic efficiency by 50 % compared with the non-plasma modified steel-slag as a catalyst for catalyzing CNTs. In addition, catalytically grown CNTs encapsulate magnetic steel-slag catalysts to form a three-dimensional CNT network structure, with high-performance electromagnetic wave absorption. The composite absorbing material with a thickness of only 3.55 mm has a minimum absorption rate of −64.08 dB for electromagnetic waves at a frequency of 7.9 GHz. The dielectric and the magnetic loss of steel-slag lead to enhanced electromagnetic wave absorption. Therefore, this study provides an inexpensive and environmentally friendly idea for the design of high-efficiency CNT growth and solid waste catalyst modification synthesized with high-performance absorbers.

Preparation of micro-meso-macroporous structured hydrangea-like cobaltous sulfide with sulphur vacancy for high-performance electromagnetic wave absorption

Preparation of micro-meso-macroporous structured hydrangea-like cobaltous sulfide with sulphur vacancy for high-performance electromagnetic wave absorption

Genome engineering of materials based on Ce doping, high-performance electromagnetic wave absorber for marine environment

Traditional microwave absorbing materials (MAM) are difficult to meet the current increasingly complex electromagnetic environment, MAM began to functionally integrated development to meet the needs of diversified applications. For the high humidity and high salt spray environment of the ocean, the development of electromagnetic absorber integrating microwave absorption (MA) and corrosion protection functions is imminent. In this work, high-quality genes were screened through materials genome engineering, and in-situ doping strategies of Ce gene were designed to synergistically enhance MA properties using composition modulation and structure modulation, the effective absorption bandwidth (EAB) of composite material WC@FCC1 can reach 5.62 GHz at an ultra-thin thickness of 1.66 mm. Thanks to the unique 4f orbital mechanism of Ce element, CeO2 is endowed with excellent redox property, forming an oxide protective film on the surface, which prevents the entry of external corrosive media. The excellent corrosion protection performance of the composite material has been verified through electrochemical testing and molecular dynamics simulation. This work provides new design ideas for high-performance MAM, as well as new strategies and insights for functionally integrated electromagnetic absorber.

Upcycling Spent Graphite from Li-ion Batteries into Cu/Expanded Graphite Composites as high-performance electromagnetic wave absorbers.

With the widespread adoption of lithium-ion batteries and modern electronic components in both daily life and industrial production, there is a growing focus on the high-value recycling of spent lithium-ion batteries and the development of absorbents with high electromagnetic wave absorption capabilities. Efficiently regenerating recycling graphite from spent batteries through low-cost methods and utilizing it to prepare high-performance electromagnetic wave absorbing materials holds significant importance in addressing both the utilization of waste graphite and electromagnetic pollution issues simultaneously. This work presents a method to transform spent graphite into expanded graphite with a three-dimensional conductive structure using an enhanced Hummer's treatment and thermal reduction process. Subsequently, Cu/EG composite materials were efficiently prepared through straightforward mechanical ball milling and calcination. The unique honeycomb-like porous structure of expanded graphite facilitates the reflection and scattering of electromagnetic waves, electron transfer, and defect polarization. Additionally, the incorporation of copper nanoparticles improves the conduction loss and enhances interface polarization, allowing for precise tuning of the composite material's absorption performance. The results demonstrate that Cu/EG composite materials exhibit excellent electromagnetic wave absorption performance. The Cu/EG(1:3) sample exhibits effective absorption in the C, X, and Ku bands, achieving a minimum reflection loss (RLmin) of -54 dB and a maximum effective absorption bandwidth (EABmax) of 5.28 GHz. This performance is attained with a thickness of just 2.2 mm and a filler content of only 15 wt.%.

A Hybrid Perovskite-Based Electromagnetic Wave Absorber with Enhanced Conduction Loss and Interfacial Polarization through Carbon Sphere Embedding.

Electronic equipment brings great convenience to daily life but also causes a lot of electromagnetic radiation pollution. Therefore, there is an urgent demand for electromagnetic wave-absorbing materials with a low thickness, wide bandwidth, and strong absorption. This work obtained a high-performance electromagnetic wave absorption system by adding conductive carbon spheres (CSs) to the CH3NH3PbI3 (MAPbI3) absorber. In this system, MAPbI3, with strong dipole and relaxation polarization, acts dominant to the wave absorber. The carbon spheres provide a free electron transport channel between MAPbI3 lattices and constructs interfacial polarization loss in MAPbI3/CS. By regulating the content of CSs, we speculate that this increased effective absorption bandwidth and reflection loss intensity are attributed to the conductive channel of the carbon sphere and the interfacial polarization. As a result, when the mass ratio of the carbon sphere is 7.7%, the reflection loss intensity of MAPbI3/CS reaches -54 dB at 12 GHz, the corresponding effective absorption bandwidth is 4 GHz (10.24-14.24 GHz), and the absorber thickness is 2.96 mm. This work proves that enhancing conduction loss and interfacial polarization loss is an effective strategy for regulating the properties of dielectric loss-type absorbing materials. It also indicates that organic-inorganic hybrid perovskites have great potential in the field of electromagnetic wave absorption.

Design of a yolk-shell ternary metal sulfide with a tunable structure for high-performance electromagnetic wave absorption.

Herein, we report a strategy for preparing a novel ternary metal sulfide (TMS) with a yolk-shell structure based on a "penetration-solidification-annealing" method. A series of FeCoNiSxGy with tunable structure, different morphology and composition was synthesized by adjusting the degree of sulfuration. Due to the synergistical manipulation of rich interface, defects, vacancies and electrical conductivity, as well as the unique yolk-shell structure, the appropriate sulfuration strategy achieved excellent impedance-matching and strong dielectric loss. The as-synthesized FeCoNiSxGy sulfides were blended with paraffin wax (under a filler loading of 30 wt%), which had the minimum reflection loss of -49.44 dB (2.20 mm) and the effective absorption bandwidth of 4.76 GHz (1.6 mm). In conclusion, this work could aid the design and regulation of a new type of ternary metal sulfides with high-performance electromagnetic wave absorption.

Sulfidation and reassembly strategy enables yolk-shell metal sulfide/alloy nanoparticles @carbon with efficient electromagnetic wave absorption

Constructing hybrid metal-organic frameworks (MOFs) demonstrates significant potential to improve electromagnetic wave (EMW) absorption performance by leveraging synergistic effects between composition and structure, addressing challenges in tuning electromagnetic parameters of single-composition MOFs. This study proposes a sophisticated strategy involving sulfidation-interface growth-reassembly: sulfide nanoparticles form by sulfidating the core (CoFe-MIL-88A), and then ZIF-67 guests grow and reassemble on the sulfided host MOF, resulting in a layered EMW absorption material. The composite material integrates synergistic effects, which include high conductive loss and defect/interface/dipole polarization induced by N and S atom doping. The CFSNC composite material outperforms previously published values, achieving a minimum reflection loss (RLmin) of −65.96 dB and an effective absorption bandwidth (EAB) of 6.15 GHz with a thickness of merely 2 mm. Simulation calculations of the real far-field radar cross-section (RCS) further validate its practical application potential. This work introduces novel ideas and methods for designing and preparing high-performance EMW absorption materials, offering both theoretical insights and practical applications.

Confined magnetic nickel nanoparticles in carbon microspheres with high-performance electromagnetic wave absorption in Ku-band

Composition and structure regulation is the primary strategy in preparing high-performance electromagnetic (EM) wave absorption materials. Herein, magnetic-dielectric synergy Ni@C microspheres were fabricated to obtain the high-performance electromagnetic (EM) wave absorption performance. Firstly, the Ni-containing precursor microspheres were obtained via the spray-drying technology. Secondly, reduced magnetic Ni nanoparticles (NPs) were confined in the N-doped carbon microspheres after pyrolysis treatment in the H2/Ar atmosphere. Duo to the existence of melamine, the distribution of Ni NPs and related EM parameters of Ni@C microspheres were efficiently regulated to seek the well impedance matching and EM responded ability. As results, as-synthesized Ni@C microspheres exhibited the minimum reflection loss (RLmin) of −48.2 dB and effective absorption bandwidth (EAB) of 5.7 GHz, covering almost Ku-band. This research represents a significant advancement in the development of magnetic-dielectric composite microspheres with superior absorption capacity, and it also provides a large-scale preparation strategy for electromagnetic wave absorbing materials.

Ultralight and rigid PBO nanofiber aerogel with superior electromagnetic wave absorption properties

Polymer-based aerogels are emerging as promising candidates for lightweight and high performance electromagnetic (EM) wave absorption materials. In this study, an ultralight and rigid poly(p-phenylene benzobisoxazole) nanofiber (PNF) based composite aerogel with excellent EM wave absorption performance was fabricated with cobalt-nickel alloy (CoNi) nanoparticles and carbon nanotubes (CNTs) as magnetic and conductive fillers, respectively. A CNT/PNF composite aerogel was first prepared through a sol-gel and freeze-drying method, and then CoNi nanoparticles were introduced therein through hydrothermal reaction and thermal annealing to obtain the CoNi/CNT/PNF aerogel. CNTs and PNFs were interwoven and constructed a three-dimensional conductive/magnetic cage-like skeleton structure decorating with magnetic CoNi nanoparticles. The cage-like skeleton structure allowed the dissipation of EM waves through multiple mechanisms encompassing conduction loss, magnetic loss, multiple reflection, scattering, and absorption. When its thickness was 4 mm, the CoNi/CNT/PNF aerogel showed a minimal reflection loss of −44.7 dB (at 6.88 GHz), and its broad effective absorption bandwidth covered the entire X-band and Ku-band and most of the C-band (12.32 GHz, from 5.68 GHz to 18 GHz). In addition, the rigid aerogel exhibited an ultralow density (0.107 g/cm3), excellent thermal insulation, and flame retardancy, demonstrating its potential application as a high-performance EM wave absorption material in the fields of aerospace and national defense.

NiCoZn/C@melamine sponge-derived carbon composites with high-performance electromagnetic wave absorption

NiCoZn/C@melamine sponge-derived carbon composites with high-performance electromagnetic wave absorption

A novel high-entropy perovskite Ba(Zn0.2Yb0.2Ta0.2Nb0.2V0.2)O3 ceramic with excellent Electromagnetic wave absorption properties

In order to solve the increasingly serious electromagnetic wave pollution, the preparation of high-performance electromagnetic wave absorbing (EWA) materials has been very urgent. High-entropy ceramics have a good prospect in the field of EWA materials due to the unique effect brought by its multi-component elements. Therefore, in this study, the composition of high-entropy ceramics was designed by utilizing the Goldschmid tolerance factor. Then the high-entropy perovskite Ba(Zn0.2Yb0.2Ta0.2Nb0.2V0.2)O3 ceramic (BZO) with high EWA performance was prepared by high-temperature solid-phase method. The EWA mechanism of the material was explored based on the phase composition, microstructure and electromagnetic parameters of the samples. Good impedance matching and better attenuation ability were obtained for BZO-1100 due to the crystallographic transition and interface increase. As a result, BZO-1100 achieves excellent EWA performance at a thickness of 2.12 mm, with a minimum reflection loss (RLmin) of −54.09 dB and an effective absorption bandwidth (EAB) of 2.81 GHz in the X-band. In addition, the possibility of the practical application of the BZO high-entropy ceramics is verified by electric field distribution simulations and RCS simulations. This study provides a valuable reference for the design of high-performance high-entropy perovskite ceramic absorber materials.

Construction of enhanced multi-polarization and high performance electromagnetic wave absorption by self-growing ZnFe2O4 on Cu9S5

Construction of enhanced multi-polarization and high performance electromagnetic wave absorption by self-growing ZnFe2O4 on Cu9S5

High-performance electromagnetic wave absorption in VS2@multi-walled carbon nanotube composites

In this work, composites comprising VS2 and multi-walled carbon nanotubes (MWCNTs) were prepared using a simple hydrothermal method. The MWCNTs were dispersed among the VS2 nanosheets, which produced dipole polarization and interfacial polarization, thus enhancing the dielectric loss. Meanwhile, the electrical conductivity of the composites gradually increased with the rising content of the MWCNTs, which improved the electromagnetic wave absorption performance. By adjusting the mass ratio of VS2 to MWCNTs to 5:1, a minimum reflection loss value (RL) of −24.7 dB was achieved with a thickness of only 1.3 mm at a frequency of 14.4 GHz. Besides, when the thickness was reduced to 1.2 mm, the effective absorption bandwidth extended to 3.75 GHz. The results suggest that impedance matching and the synergistic effect of multiple loss mechanisms contribute to the excellent electromagnetic wave absorption performance of the materials. Consequently, the VS2/MWCNTs composites exhibit simple synthesis, wide absorption bandwidth, thin thickness, and high absorption capacity, rendering them a promising material for practical microwave absorption applications.

Low-frequency and broadband electromagnetic wave absorption mechanism of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ/PyC microspheres with hierarchy pores from 4 GHz to 17 GHz

Achieving low-frequency broadband electromagnetic wave absorption in extreme environments over 2000 °C is challenging. Biomimetic hierarchy materials of high entropy lanthanide carbides were designed to optimize electromagnetic wave absorption. Composite microspheres of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ and SiC embedded in pyrolytic carbon (MC/PyC) were prepared by using the electro-spray method followed by heat treatment. The specimens of MC/PyC microspheres with a thickness of 2.5 mm exhibited a minimum reflection loss value of − 48.9 dB, and electromagnetic wave absorption from 4.0 GHz to 17 GHz. The enhanced absorption capability is attributed to the synergistic effect of dielectric losses from conduction and polarization, along with magnetic losses due to eddy currents and natural resonance of the high-entropy carbides within the multiscale pores. The composition and featured microstructure MC/PyC microspheres were noteworthily stable under the 2200 °C oxyacetylene ablation, ensuring consistent high-performance electromagnetic wave absorption even in harsh conditions.

Fe3O4 Nanoparticles Embedded into Pyridinic-N-Rich Carbon Nanohoneycomb with Strong dx2-Pz Orbital Hybridization for High-Performance Electromagnetic Wave Absorption.

Carbon-based magnetic nanocomposites as promising lightweight electromagnetic wave (EMW) absorbents are expected to address critical issues caused by electromagnetic pollution. Herein, Fe3O4 nanoparticles embedded into a 3D N-rich porous carbon nanohoneycomb (Fe3O4@NC) were developed via the pyrolysis of an in-situ-polymerized compound of m-phenylenediamine initiated by FeCl2 in the presence of NaCl crystals as templates. Results demonstrate that Fe3O4@NC features highly dispersed Fe3O4 nanoparticles into an ultrahigh specific pyridinic-N doping carbon matrix, resulting in excellent impedance matching characteristics and electromagnetic wave absorbing capability with the biggest effective absorption bandwidth (EAB) of up to 7.1 GHz and the minimum reflective loss (RLmin) of up to -65.5 dB in the thin thickness of 2.5 and 2.3 mm, respectively, which also outperforms the majority of carbon-based absorbers reported. Meanwhile, its high absorption performance is further demonstrated by an ethylene propylene diene monomer wave absorbing patch filled with 8.0 wt % Fe3O4@NC, which can completely shield a 5G signal in a mobile phone. In addition, theory calculation reveals that there is a strongest dx2-Pz orbital hybridization interaction between Fe3O4 clusters and pyridinic-N dopants in the carbon network, compared with other kinds of N dopants, which can not only generate more dipoles of carbon networks but also increase net magnetic moments of Fe3O4, thereby leading to a coupling effect of efficient dielectric and magnetic losses. This work provides new insights into the precise design and synthesis of carbon-based magnetic composites with specific interface interactions and morphological effects for high-efficiency EMW absorption materials.

Hierarchical porous SiCnws/SiC composites with one-dimensional oriented assemblies for high-temperature broadband wave absorption

The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity. Herein, the lightweight silicon carbide nanowires (SiCnws)/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiCnws skeleton, which collaborative configuration by 3D printing and freeze casting assembly. The constructed porous structure optimizes the impedance matching degree and scattering intensity, the maximum effective absorption bandwidth (EABmax) of 5.9 GHz and the minimum reflection loss (RLmin) of −41.4 dB can be realized. Considering the inherent oxidation resistance of SiC, the composites present well-maintained absorption performance at 600 °C. Even at 1100 °C, the EABmax of 4.9 GHz and RLmin of −30.4 dB also demonstrate the high-temperature absorption stability of the composites, indicating exceptional wave absorption properties and thermal stability. The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant. This work clarifies the impact of structure and component synergy on wave absorption behavior, and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.

Green-prepared high-performance electromagnetic wave absorption Ni6W6C/Co2O3@C composites and related broadband absorption device

In recent years, the synthesis of absorbing materials using green and environmentally friendly natural raw materials have become a research topic, but green and environmentally friendly materials with both high performance and simple synthesis steps still need to be developed. In this work, glucose and metal organic framework (MOF) were used to prepare composite materials with strong absorbing ability and low cost. We chose glucose, which is convenient to purchase on the market, as the raw material and constructed MOF derivatives with carbon shell skeleton nanostructures through a simple method of hydrothermal and annealing. Compared to the raw materials of traditional absorbing materials, glucose has environmentally friendly, low-cost and green characteristics. We characterized the microstructure and morphology of the material. In addition, we also analyzed the material composition and absorption mechanism of Ni6W6C/Co2O3@C. We have found from the theoretical analysis and simulation results of transmission lines that the minimum reflection loss (RLmin) value of Ni6W6C/Co2O3@C material at 5.43 GHz and 4.76 mm is −56.68 dB. And the effective absorption bandwidth (EAB) at 2.04 mm can reach 7.12 GHz. We load the best sample to the honeycomb structure, a broadband microwave absorber was designed for simulation. The results show that the broadband microwave absorber can achieve an average electromagnetic wave (EMW) loss of more than 99 % in the 0.3–16.04 GHz frequency band (RL value is less than −20 dB), and an average EMW loss of more than 90 % in the 16.04–18 GHz frequency band (RL value less than −10 dB). The composite structure of glucose and MOF derivatives enhances the dielectric loss of the material and enriches various EMW loss mechanisms. Finally, a green, environmental-friendly, high-performance absorbing material with a simple synthesis method is prepared. These results provide insights into the research on EMW absorption of composite materials and new methods for referring.

Plentiful heterogeneous interfaces coupling in hydrangea-like NiMn-LDH decorated MXene hybrids for enhancing electromagnetic wave absorption

Exploring high-performance electromagnetic wave (EMW) absorption materials holds extraordinary potential for new-generation wireless communication and integrated electronics. Herein, a series of heterogeneous hydrangea-like NiMn-layered double hydroxide (NiMn-LDH)/MXene (denoted as NMM) hybrids were successfully synthesized by facile hydrothermal method and followed electrostatic self-assembly strategy. The EMW absorption performance of NMM hybrids could be flexibly tuned by regulating the ratios of NiMn-LDH to MXene. Benefiting from the synergy of unique structural design and various EMW attenuation mechanisms, the resultant NMM hybrids realize excellent EMW absorption performance. The NMM3 hybrid (the ratio of NiMn-LDH to MXene is 1:1) achieves an optimal reflection loss of −47.7 dB at 13.29 GHz with a thickness of 1.68 mm and a broad effective absorption bandwidth of 4.4 GHz (13.6–18.0 GHz) at a tiny thickness of 1.43 mm. Moreover, the radar cross section simulation is used to intuitively reveal the effectiveness of NMM hybrids as high-performance EMW absorption materials in actual application. This work provides an innovative perspective on the controllable design of highly efficient EMW absorption materials with remarkably practical application value.