Efficient Electromagnetic Absorption Research Articles

Biomass-derived mulberry porous carbon for microwave absorption

In modern electronic devices and communication systems, there is an urgent need for economically viable, environmentally friendly, and efficient absorbing materials. In this work, we have successfully synthesized nitrogen-potassium doped mulberry porous carbon (MBPC) using a one-step pyrolysis strategy for the first time utilizing mulberry as a biomass carbon wave-absorbing material. The resulting MBPC exhibited a porous structure with abundant defects, facilitating the formation of a micro-conductive network and multiple reflection and scattering phenomena, thereby enabling strong microwave absorption. Experimental results demonstrated that the MBPC material achieved a remarkable minimum reflection loss of −44.82 dB at a frequency of 14.64 GHz, along with a maximum effective absorption bandwidth exceeding 5.76 GHz, all within a thickness of only 2.2 mm. Furthermore, by adjusting the thickness between 1 ∼ 3 mm, the bandwidth coverage can be extended to 8.48 ∼ 18 GHz. Computer simulation technology (CST) revealed a high simulated RCS value of 20.68 dB·m2, highlighting its significant practical application potential. This research underscores the promising prospects of mulberry-derived porous carbon as a lightweight, cost-effective, and efficient electromagnetic absorption material.

Constructing core-shell carbon fiber/polypyrrole/CoFe2O4 nanocomposite with optimized conductive loss and polarization loss toward efficient electromagnetic absorption

Constructing core-shell carbon fiber/polypyrrole/CoFe2O4 nanocomposite with optimized conductive loss and polarization loss toward efficient electromagnetic absorption

Rough‐Endoplasmic‐Reticulum‐Like Hierarchical Composite Structures for Efficient Mechanical‐Electromagnetic Wave‐Energy Attenuation

AbstractInspired by a critical organelle called rough endoplasmic reticulum (RER), a wave‐energy attenuation nano‐carbon foam (WANF) with a unique hierarchical composite structure consisting of 3D‐lamelle, 2D‐perforations and 1D‐microspheres is constructed by incorporating graphene oxide (GO) and polydimethylsiloxane (PDMS) into a carbon nanotubes (CNTs)‐based aerogel. Benefiting by unusual mechanisms like vortex shedding, secondary reflection and resonance, WANF displays excellent acoustic wave absorption, achieving a sound absorption coefficient of over 0.9 with a bandwidth of 4.75 kHz at a thickness of 20 mm. Significantly, it features obvious acoustic absorption intensity in medium‐low frequency range. Moreover, the nano‐carbon aerogel skeleton (NCAS) of WANF endows it with good electromagnetic wave absorption through dielectric loss, exhibiting a minimum reflection loss of −48.61 dB and an efficient electromagnetic absorption with a bandwidth of 5.35 GHz. The excellent wave‐energy attenuation performance of WANF indicates an attracting double‐stealth effect in sonic and electromagnetic area, which shows great potential in integrate protection of advanced military equipment and sensitive electronic infrastructures.

Multifunctional WSe2/Co3C composite for efficient electromagnetic absorption, EMI shielding, and energy conversion

Multifunctional WSe2/Co3C composite for efficient electromagnetic absorption, EMI shielding, and energy conversion

GR-Fe3O4/PLA 3D printing composite materials with excellent microwave absorption properties

In this work, composite microspheres were formed by integrating graphene (GR) and Fe3O4 into an ethylcellulose matrix via an emulsion emulsification reaction. Composite wires were fabricated using a melt extrusion process and composite samples were subsequently prepared via a melt molding method. A systematic study was conducted to investigate the absorption performance of GR-Fe3O4/PLA (Polylactic acid) composite materials. The findings revealed that the optimal microwave absorption performance was achieved when the graphene content was 5.6 wt% and the Fe3O4 content was 11.1 wt%. The maximum reflection loss was − 51.13 dB at a thickness of 2.65 mm. The maximum absorption bandwidth was 4.16 GHz, and the effective radar interception cross-section was reduced to − 42.7 dBm2. The excellent performance of GR-Fe3O4/PLA composite material can be attributed to good impedance matching and the synergistic effect of conductive loss, dipole polarization, interface polarization, and eddy current loss. Then the contribution of conductive loss and polarization loss to the absorption performance was explored. This work provides a novel approach to advance the design and development of functional materials for efficient electromagnetic absorption, providing valuable insights into the development of efficient, lightweight microwave absorbing material.

Fabrication of Co/C composites derived from Co-based metal organic frameworks with broadband and efficient electromagnetic absorption

Fabrication of Co/C composites derived from Co-based metal organic frameworks with broadband and efficient electromagnetic absorption

Functional additive manufacturing of large-size metastructure with efficient electromagnetic absorption and mechanical adaptation

Broadband microwave absorption as a hot research topic plays important roles on electromagnetic compatibility, electromagnetic radiation protection and radar detection disguise. However, traditional molding method is difficult to fabricate large-size curving structures for broadband microwave absorption. Herein, the material extrusion with high-speed printing process was effective to manufacture large-size metastructures for broadband microwave absorption. The polylactic acid was mixed and extruded with nano pyrolytic carbon in high temperature to manufacture functional filaments with high dielectric loss. The printed metastructure integrated with 0.5 mm quartz fiber reinforced composite (QFRC) achieved -10 dB broadband microwave absorption in 3.03-18 GHz and effective load bearing performance in tensile and flexural tests. Severe impedance mismatch brought by QFRC was overcome by appropriate structure design and high-speed printing technique. The proposed design-manufacturing closed loop is a promising approach to fabricate aircraft skin with broadband microwave absorption performance and suitable aerodynamic properties for heavy unmanned aerial drones.

FeNi/C/TiO2 composites derived from [Fe(pz)Ni(CN)4] Hofmann framework and MXene for efficient electromagnetic absorption

Chemical composition and morphological optimization are both effective strategies for constructing excellent electromagnetic wave absorption (EMWA) materials. While efficient EMWA materials derived from both metal-organic frameworks (MOFs) and MXenes have been extensively studied, composites derived from the Hofmann framework with MXene have not been reported. In this study, we employed a Hofmann framework ([Fe(pz)Ni(CN)4], pz = pyrazine) and MXene (Ti3C2Tx) to create new MXene@Hofmann (MH1 and MH2) composites, using a simple co-precipitation method with two different contents of [Fe(pz)Ni(CN)4]. The FeNi/C/TiO2 composites with a multi-layered structure inherited from MXene were prepared by annealing the MXene@Hofmann composites at 500, 600, and 700 °C, resulting in the formation of MH1-500/600/700 and MH2-500/600/700 composites. Their compositions, morphologies, electromagnetic parameters, and EMWA performances were characterized. For the composites with a high [Fe(pz)Ni(CN)4] content, MH2-600 has a minimum reflection loss (RLmin) value of −30.63 dB at a thickness of only 1.8 mm and the broadest effective absorption bandwidth (EAB) of 3.90 GHz at 2.0 mm, while MH2-700 exhibits superior EMWA performance with an RLmin value of −34.34 dB at 1.9 mm and an EAB value of 4.96 GHz at 2.1 mm. Their impressive EMWA performance might be attributed to the synergistic dielectric loss and magnetic loss and also the impedance matching from the reasonable ratio of the magnetic and dielectric components. This work demonstrates an effective strategy for constructing EMWA materials from the Hofmann framework and MXene.

Soft matter with magnetically oriented macro - micro structure for improving microwave absorption efficiency

The key challenge for the most widely used magnetic absorbers is how to simultaneously combine low filling with efficient electromagnetic absorption performance. This paper exploited carbonyl iron particles (CIPs) to develop some soft material that possessed orderly orientated structure via applying an external excitation signal, so as to reduce hyperosmotic threshold of conductive loss network, improve impedance matching pattern and thus modulate absorption efficiency. The arch test results showed that effective absorption band (EAB, RL<−10 dB) and reflection loss (RL) efficiency of oriented structure (40 wt%−300mT sample) was much higher than that of unoriented structure (60 wt%−0mT sample), and the reflection loss intensity was reduced to − 15.2 dB, especially EAB was expanded by 8.1 GHz, which significantly alleviated the critical conflict between low filling and electromagnetic loss performance. Also, it was attempted to reveal surface topography changes caused by multiple magnetized particles interaction, and how excitation signal intensity, magnetic particles filling concentration and structural parameters affect microwave absorption efficiency and bi-directional frequency conversion. Thus, a magnetic-manipulated absorbing material proposed laid a theoretical foundation for improving loss efficiency of magnetic materials at low filling concentration.

Synthesis, characterization, and optimization of a quaternary nanocomposite for efficient electromagnetic absorption coating in the X-band

Abstract In this study, a quaternary composite of graphite, polyaniline, cobalt ferrite, and thermoplastic polyurethane as a shielding material was prepared. The composite materials were analyzed with X-ray diffraction, field emission scanning electron microscopy, vibrating-sample magnetometer and thermogravimetric analysis. The electromagnetic characterization of the samples was achieved using a Vector Network Analyzer in the X-band. The composites’ conductivity was analyzed by using the four-point probe method. For the investigation of water absorption, the ASTM D570-98 Standard Method was used. Design-Expert software applied design optimization for broadband electromagnetic shielding of the composite film. Ultimately, we introduced a composite film as an efficient microwave absorbent that had a weight percentage of cobalt ferrite 6.95 %, polyaniline 20.04 %, graphite 12.13 %, and thermoplastic polyurethane 60.88 % in a thickness of 1.26 mm, which had shielding effectiveness higher than 30 dB, which was suitable for commercial purposes. The results showed that graphite played an essential role in increasing the composite’s electrical conductivity and thermal stability but was unsuitable for water absorption resistance.

Synthesis of hollow CuFe2O4 microspheres decorated nitrogen-doped graphene hybrid composites for broadband and efficient electromagnetic absorption

The development of graphene-based electromagnetic wave (EMW) absorbers with broad bandwidth, strong absorption and low filling ratio remains a big challenge. In this work, hollow copper ferrite microspheres decorated nitrogen-doped reduced graphene oxide (NRGO/hollow CuFe2O4) hybrid composites were prepared by a two-step route of solvothermal reaction and hydrothermal synthesis. Results of microscopic morphology analysis showed that the NRGO/hollow CuFe2O4 hybrid composites had a special entanglement structure between hollow CuFe2O4 microspheres and wrinkled NRGO. Moreover, the EMW absorption properties of as-prepared hybrid composites could be regulated by changing the additive amounts of hollow CuFe2O4. It was worth noting that when the additive amount of hollow CuFe2O4 was 15.0 mg, the attained hybrid composites showed the optimal EMW absorption performance. The minimum reflection loss reached up to −34.18 dB at a thin matching thickness of 1.98 mm and a low filling ratio of 20.0 wt%, and the corresponding effective absorption bandwidth was as large as 5.92 GHz, covering almost the whole Ku band. Furthermore, when the matching thickness was increased to 3.02 mm, the EMW absorption capacity was significantly enhanced, and the optimal reflection loss value of −58.45 dB was achieved. In addition, the possible EMW absorption mechanisms were proposed. Therefore, the structural design and composition regulation strategy presented in this work would provide a great reference value for the preparation of broadband and efficient graphene-based EMW absorbing materials.

In situ construction of complex spinel ferrimagnet in multi-elemental alloy for modulating natural resonance and highly efficient electromagnetic absorption

The contradiction between the demand for highly efficient low-frequency electromagnetic wave (EMW) absorption materials and the relatively poor permeability of existing absorbers has become increasingly prominent. However, the intrinsic natural resonance in magnetic material hinders the modulation and enhancement of permeability. Herein, (FeCoNiCu)xCr3−xO4 complex spinel ferrimagnets (CSFMs) are constructed in situ in multi-elemental alloy powders (MEAs) for the first time, via annealing treatment. The microstructure and composition of the CSFMs are regulated by adjusting the annealing temperature, aiming to modulate the natural resonance frequency and achieve highly efficient megahertz (MHz) electromagnetic absorption. Simultaneously, annealing treatment improves the crystal integrity, which is conducive to enhancing intergranular magnetic coupling to elevate permeability temperature stability and the Curie temperature. The minimum reflection loss value of the MEAs/CSFMs composites is less than −7 dB at 3 mm and the effective EMW absorption bandwidth maintains between 425 and 470 MHz at 5 mm from −50 to 150 °C. In addition, the MEAs/CSFMs composites also exhibit excellent oxidation resistance and corrosion resistance due to the oxide layer on the surface. This work offers a new and tunable strategy toward modulating the natural resonance frequency for efficient temperature-stable broadband EMW absorption at specific frequency bands.

Interfacial electronic heterostructure engineering of cobalt boride nanosheets toward broadband efficient electromagnetic absorption

Vigorous reflection loss (RL), wide bandwidth together with suitable absorption frequency band are key application indicators for cutting-edge electromagnetic (EM) absorbers to avoid EM pollution in the aerospace. However, the rational design of EM absorbers, especially for the integration of multiple properties, remains highly challenging. Here, we report a novel two-dimensional (2D) nanosheets-like heterostructure constructed by a molten salt-assisted dissolution-growth strategy and linked via strong interfacial electronic interactions, namely, cobalt boride (CoB) with boron, nitrogen co-doped carbon (CoB/BNC). Density functional theory (DFT) calculations demonstrate that stable heterointerfaces formed by strong interfacial electronic interactions are beneficial for enriching polarization effects, while contributing sufficient dielectric loss to boost the EM absorption (EMA) performance. Accordingly, the minimum RL (RLmin) of −70.76 dB and effective absorption bandwidth (EAB) of 4.72 GHz are simultaneously accomplished for CoB/BNC at the thickness of 3.48 mm. Moreover, radar cross section (RCS) simulation results confirmed that the as-prepared absorber coating could perfectly suppress the metal scattering sources in different directions. Generally, this work offers an ingenious engineering strategy for the precise synthesis of functional heterostructures, which holds great promise for developing innovative EMA materials in the aerospace.

In-situ synthesis method of three-dimensional silicon/reduced graphene oxide semiconductor nanohybrids for efficient electromagnetic absorption

3D Si/rGO semiconductor nanohybrids were built from the in-situ synthesis of silicon dioxide (SiO2) and graphene oxide (GO) through magnesium thermal reduction. The incorporation of Si/rGO into a three-dimensional structure was connected by hydrogen-bonding from Si/rGO and PVA. SEM and TEM images indicated the three-dimensional structure of the samples. FT-IR, XPS, DSC, BET and UV–Vis spectra revealed the presence of Si semiconductor that was doped into the surface and edge of rGO frameworks. The electromagnetic absorbing property and the complex permittivity could be controlled by adjusting the content of Si. The maximum RL of the wax composite filled with 20 wt% 3D Si/rGO was −55.48 dB at 8.61 GHz and 2.75 mm, and the effective bandwidth reached 4.69 GHz at 1.5 mm. The three-dimensional structure of the semiconductor nanohybrids provided multiple transmission channels and reflection interfaces which could consume significant amount of microwave energy. Decorating of Si in this structure supplies high dielectric loss tangent and excellent impedance matching property, and provides highly efficient dielectric lightweight material without adding magnetic substance. This work demonstrates that in-situ synthesis method is a facile and efficient strategy to obtaining optimal electromagnetic absorbing property and mechanical property of 3D Si/rGO semiconductor nanohybrids.

Corrosion-Resistant Graphene-Based Magnetic Composite Foams for Efficient Electromagnetic Absorption.

Designing and fabricating high-performance microwave absorption materials with efficient electromagnetic absorption and corrosion resistance becomes a serious and urgent concern. Herein, novel corrosion-resistant graphene-based carbon-coated iron (Fe@C) magnetic composite foam is fabricated via self-assembly of iron phthalocyanine/Fe3O4 (FePc hybrid) on the graphene skeletons under solvothermal conditions and then annealing at high temperature. As a result, the rational construction of a hierarchical impedance gradient between graphene skeletons and Fe@C particles can facilitate the optimization in impedance matching and attenuation characteristic of the foam, realizing the efficient dissipation for incident electromagnetic waves. Additionally, the performance of electromagnetic absorption can be controllably regulated by optimizing annealing temperature and/or time. More importantly, the formation of a carbon-coated iron structure substantially improves the corrosion resistance of magnetic particles, endowing the composite foam with excellent stability and durability in microwave absorption performance.

Preparation of Three-Dimensional Mo2C/NC@MXene and Its Efficient Electromagnetic Absorption Properties.

The positively charged MoO3/PDA microspheres are obtained by stacking and assembly of the sheet structure, and the negatively charged MXene nanosheets are wrapped on the surface through the principle of electrostatic self-assembly. After annealing, a nitrogen-doped carbon composite and a MXene-coated Mo2C wave absorber are obtained. The formation of the wrinkled surface provides a complex pore structure, and the multiple interface reflections between the nanosheets enhance the absorption performance. The existence of heterogeneous interfaces and the uneven distribution of space charges accumulated between the interfaces effectively reduce the minimum reflection loss (RLmin). This work explores the effects of the ratio between MoO3/PDA and MXene nanosheets and loading amount on the microwave absorption properties. Mo2C/NC@MXene-2 obtained when the ratio of the two is 3:1 has the best absorption performance under 25% loading. The RLmin is -59.36 dB, and the corresponding effective absorption bandwidth (EAB) is 4.6 GHz at 2.5 mm. This work expands the new applications of MXene-based and Mo2C-based materials and has a guiding significance for the design of electrostatic self-assembly materials.

Design of porous FeNi-carbon nanosheets by a double-effect synergistic strategy for electromagnetic wave absorption

The electromagnetic pollution problem caused by the wide application of electromagnetic waves has seriously affected human life and prompted people to research efficient electromagnetic absorption materials. In this work, a porous FeNi-carbon nanosheet was designed and synthesized by a double-effect synergistic strategy. The three raw materials achieved perfect structural synergy, organically combining the magnetic medium with carbon materials. FeNi nanoparticles are evenly distributed on hierarchical pore carbon nanosheets. This unique structure dramatically reduces the materials’ density and improves impedance matching. The minimum density of porous FeNi-carbon nanosheets (FeNi-CNSs) is 36.3 mg cm3, comparable to that of carbon aerogels. More importantly, the synergistic attenuation mechanism of dielectric loss and magnetic loss promotes the efficient attenuation of FeNi-CNSs to electromagnetic waves. The minimum reflection loss (RLmin) of FeNi-CNSs is −47.27 dB at 3.0 mm, and the effective absorption bandwidth (EAB) is as high as 7.1 GHz at 2.5 mm. More surprisingly, when the thickness is in the range of 1.8–3.0 mm, the average EAB reaches 6.22 GHz, which expands the operational range of practical applications and provides the possibility for the application and promotion of lightweight magnetic carbon nanosheet microwave absorbing materials.

SiC network reinforced SiO2 aerogel with improved compressive strength and preeminent microwave absorption at elevated temperatures

Improved compressive strength and preeminent microwave absorbing properties are of great importance to meet the harsh requirements of the thermal environment. Herein, the SiC network reinforced SiO2 aerogel composites were synthesized via the carbonation, chemical vapor deposition, and sol-gel process using melamine sponge as the precursor and carbon foam as the structural template, followed by a heat treatment in the elevated temperature range of 300–1200 °C. The results showed that the compressive performance was significantly enhanced as a superior compressive response of 3.46 MPa at 9.49 % strain was obtained owning to the strengthened SiC skeleton wrapped by the SiO2 aerogel with the rising temperature. Besides, the composite after being warmed at 900 °C was provided with an efficient electromagnetic absorption capacity with a minimum reflection loss value of −55.38 dB at 16.56 GHz and a maximum effective frequency bandwidth of 8.16 GHz at 4.10 mm, resulting from the optimal attenuation constant as well as superior impedance matching ratio. Given the outstanding compressive strength and microwave absorbing characteristics, the aerogel composite has a good prospect in the complex electromagnetic fields.

Covalent organic framework-derived hollow core-shell Fe/Fe3O4@porous carbon composites with corrosion resistance for lightweight and efficient microwave absorption

The functionalization of covalent organic frameworks (COFs) has recently captured great attention due to their designable structures and high specific surface area. However, their application in the field of microwave absorption is still scarce. In this work, hollow core-shell Fe/Fe3O4@porous carbon composites were successfully synthesized by calcining Fe3O4@COF composites. The composite obtained after heat treatment inherits the characteristics of porous and high specific surface area of the COF material, and the hollow core-shell porous structure facilitates multiple reflections and scattering of electromagnetic waves, the increase of active center sites, and the improvement of impedance matching. The results demonstrate that the composite exhibits efficient electromagnetic absorption performance at ultra-thin matching thickness (d = 1.8 mm): the minimum RL value is -50.05 dB and the effective absorption bandwidth is 5.20 GHz. Meanwhile, the absorption band with RL < -10 dB covers almost the whole C, X and Ku bands with varied thicknesses (1.50 ~ 5.00 mm). In addition, owing to the protective effect of the COF-derived carbon shell, the material exhibits improved stability of composition, structure and properties in harsh environments. This work may further develop the functionalization of COF materials, and facilitate the development of stable core-shell materials with improved electromagnetic wave absorption properties.

MIL-100(Fe) decorated on graphene using as wideband microwave absorption material

Microwave absorption materials have attracted significant attention because of potential application in military stealth and information safety. In this work, MIL-100(Fe)/Graphene composite was successfully synthesized by a facile method and the microwave absorption mechanism were studied systematically. The as-prepared MIL-100(Fe)/Graphene shows excellent microwave absorption properties with a minimum reflection loss value of −50.9 dB at 13.6 GHz for absorber thickness of 1.8 mm. Moreover, the absorption peak frequency and effective microwave absorption region (< −10 dB) can be controlled in the range of 3.6-18.0 GHz by varying the thickness of the absorber. The highly efficient electromagnetic absorption performance of the MIL-100(Fe)/Graphene is mainly attributed to the enhanced impedance matching. The MIL-100(Fe)/Graphene composite has a great potential applied in the field of microwave absorption.