High-performance Electromagnetic Absorption Research Articles

Reduced graphene oxide/nonwoven fabric filled honeycomb composite structure for broadband microwave absorption

The prevalence of electromagnetic pollution in daily life has led to a rapid escalation in the demand for high-performance electromagnetic absorption and protection materials. Herein, a composite material consisting of reduced graphene oxide (RGO)/nonwoven absorbent was prepared and filled into honeycomb structures. The single-layer nonwoven/honeycomb composite, with a thickness of 5 mm, demonstrates an effective absorption bandwidth (reflection loss ≤ −10 dB) reaching 12.1 GHz (5.9 GHz–18 GHz) and a minimum reflection loss of −37 dB. This is attributed to the synergistic absorption effects of conduction loss, interfacial scattering, dielectric relaxation, and multiple scattering losses. Furthermore, the bilayer composite structure demonstrates the capability to achieve full band absorption of 2 GHz–18 GHz with a thickness of only 10 mm, giving carbon materials a thin and lightweight absorption effect. In addition, the composite materials exhibit excellent mechanical properties. This study presents a new idea for the design and manufacture of broadband, lightweight, and high-performance microwave absorbers, which holds significant potential in the field of electromagnetic pollution prevention and absorption.

Hierarchical Flower-like Sulfides with Increased Entropy for Electromagnetic Wave Absorption.

The concept of high entropy is considered promising to enhance electromagnetic wave absorption properties. However, preparing high-entropy sulfides with unique structures for high-performance electromagnetic absorption remains a challenge. In this study, hierarchical porous flower-like dual-phase sulfides were designed with increased entropy and fabricated using a versatile approach. The porous flower configuration enhanced the scattering of electromagnetic waves and the impedance-matching characteristics. Additionally, the effect of high entropy induced diverse defects that were favorable for electromagnetic wave dissipation in dual-phase sulfides. The design of the dual-phase structure generated strong interface polarization, and the composition and content of the phases exhibited clear changes with the increase in the number of metal elements. Interestingly, apparent lattice distortions, defects, and shear strains were directly observed near the dual-phase interface of millerite (102) and pyrite (220) planes, facilitating the occurrence of dipole polarization. Consequently, the developed dual-phase high-entropy sulfide exhibited outstanding microwave absorption properties. The minimum reflection loss value of (FeCoNiCuZn)S was -45.8 dB at a thickness of 1.5 mm, and the optimal effective absorption bandwidth was 3.8 GHz at a thickness of 1.4 mm thickness. Thus, the design of high-entropy sulfides brings meaningful guidance for tuning the wave absorption properties in sulfides.

Biomass-based porous carbon with surface grown MXenes for high-performance electromagnetic absorption and supercapacitor validated from structural and charge changes

Biomass-based porous carbon with surface grown MXenes for high-performance electromagnetic absorption and supercapacitor validated from structural and charge changes

Size-regulated Co-doped hetero-interfaced 3D honeycomb MXene as high performance electromagnetic absorber with anti-corrosion performance

It is desirable to develop electromagnetic (EM) wave absorbers with anti-corrosion property that can suit various electronics, telecommunications, and military applications in harsh conditions. In this work, by varying the Co content in the 3D honeycomb MXene, Co/MXene composites with remarkable EM absorption performance were obtained. In particular, Co/MXene with 0.5 mmol Co displayed a minimum reflection loss (RL) of –54.3 dB at 2.34 mm and broad absorption bandwidth of 5.92 GHz at 2.02 mm. These Co/MXene composites also showed high resistance to corrosion as evidenced by very low corrosion current densities (10−6 ∼ 10−7 A cm−2) and very large polarization resistances (107 ∼ 108 Ω) when exposed to various corrosive conditions (acid, neutral, and alkaline conditions). The unique honeycomb architecture and the combined presence of Co and MXene enabled the electron transfer from Co to MXene as revealed by density functional theory simulation and suppressed the contributions from magnetic and conductive losses, thus allowing only polarization loss-originated EM dissipation behavior. Accordingly, this study introduces a simplified model to elucidate the mechanism of EM absorption, offering insights at the nano level.

Amorphism SiBON interface anchored rGO nanoplatelets composites with tunable electromagnetic properties for microwave absorption

Benefiting from a particular ceramic/graphene interface anchored structure, SiBON/reduced graphene oxide nanoplatelets (RGNPs) composite was successfully designed. The electromagnetic wave is smoothly introduced into the composite from the outer layer composed of wave transmission ceramics and attenuated from the inner RGNPs layer, which solves the high impedance matching characteristic of RGNPs. With high-performance electromagnetic absorption, the composites are synthesized by an innovative chemical grafting method, and its absorbing mechanism is discussed. The SiO2 (110) lattice plane is oriented to the edge of RGNPs using the preferred orientation when forming SiBON ceramic. A composite structure is formed with SiBON as external antenna poles and RGNPs as internal signal processors. The interaction between different dielectric loss mechanism balances is achieved by adjusting the content of the ceramic. Results prove that the composite has the best electromagnetic wave absorption performance, when the mass ratio of SiBON ceramics to RGNPs is 1:10, and the filling amount is 20 wt%, forming a broad absorption band (4.80 GHz, 12.88 GHz–17.68 GHz). When the mass ratio of SiBON ceramics to RGNPs is 1:40, the maximum reflection loss is −50.43 dB (13.44 GHz) at a small thickness (1.7 mm).

Designing of an rGO-based heterostructure for highly efficient microwave absorption performance and flame retardancy

To meet the increasingly serious challenges of electromagnetic pollution and fire hazards, highly efficient electromagnetic absorbing materials with good flame retardancy have been accurately developed. A complex high-performance electromagnetic absorber was designed by doping graphene oxide heterostructures (including zero-dimensional nanoparticles and two-dimensional graphene) containing cobalt, nickel and iron oxyhydroxide through the coordination effect. When 20 wt% CNFO@rGO was incorporated into paraffin, the minimum reflection loss (RL) reached -51.6 dB at a thickness of 3.5 mm, showing a high electromagnetic absorption efficiency. It was concluded that the excellent impedance matching, the best dielectric loss and the higher magnetic loss caused by the heterostructure combined with the electromagnetic parameters, Cole-Cole semicircle, impedance matching (Z) and attenuation coefficient resulted in excellent electromagnetic wave absorption performance. Moreover, the peak heat release (PHRR) and heat release rate (HRC) decreased by 55.5% and 55.1%, respectively, when 10 wt% CNFO@rGO was incorporated into the epoxy resin (EP), indicating enormous potential for the enhancement of flame-retarding electromagnetic absorbing materials.

High-performance composite elastomers with abundant heterostructures for enhanced electromagnetic wave absorption with ultrabroad bandwidth

Two-dimensional (2D) MXene has attracted vast attention in electromagnetic wave absorption (EWA), but there remains a contradiction between maintaining impedance matching and enhancing dielectric loss. Herein, the multi-scale architectures of ecoflex/2D MXene (Ti3C2Tx)@zero-dimensional CoNi sphere@one-dimensional carbon nanotube composite elastomers were successfully constructed by simple liquid-phase reduction and thermo-curing method. The binding between the hybrids as fillers and ecoflex as a matrix greatly enhanced the EWA capability of the obtained composite elastomer and improved its mechanical properties. Owing to its good impedance matching, abundant heterostructures, and synergistic electrical and magnetic losses, this elastomer exhibited an excellent minimum reflection loss of −67 dB at 9.46 GHz under a thickness of 2.98 mm. In addition, its ultrabroad effective absorption bandwidth reached 6.07 GHz. This achievement will pave the way for the exploitation of multi-dimensional heterostructures as high-performance electromagnetic absorbers with superior EWA ability.

Investigating the Effect of Changing the Nanostructure of the Core in the Core–Shell Assembly for High-Efficiency Electromagnetic Wave Absorbers

The magnetic-dielectric core–shell structure is considered to achieve high-performance electromagnetic absorption due to the ability to use a wide range of materials and different geometrics. In this work, the effects of various nanostructures of cores on the electromagnetic absorption behavior of magnetic-dielectric core–shell structures are investigated. Herein, a BaFe12O19@MoS2 core–shell was synthesized by a hydrothermal method, and for preparing BaFe12O19 as a core with two different geometrics, the hydrothermal and sol–gel methods are used. The minimum value of reflection loss (RLmin) for BaFe12O19@MoS2, where the hexaferrite core is prepared as a nanostructure, is −53.36 at 13.1 GHz (Ku band), and the absorption bandwidth is 4.6 GHz (11.0–15.6 GHz) at a 2.0 mm thickness. Meanwhile, for BaFe12O19@MoS2, in which the structure of its core is a nanostructure (a hexagonal plate-like structure), RLmin is −41.71 at 5.1 GHz (C band), and the absorption bandwidth is 2.0 GHz (4.3–6.3 GHz) at 5.0 mm. However, in our research, by changing the size and geometry of the core nanostructures, a suitable reflection loss with an appropriate absorption bandwidth is obtained in C or Ku band frequencies.

Synthesis of FeCoNi/C decorated graphene composites derived from trimetallic metal-organic framework as ultrathin and high-performance electromagnetic wave absorbers.

High-temperature pyrolysis of metal-organic framework (MOF) is an effective way to prepare lightweight and high-performance electromagnetic wave absorbers. In this work, iron cobalt nickel/carbon (FeCoNi/C) decorated graphene composites were fabricated by the two-step method of solvothermal reaction and pyrolysis treatment. Results of micromorphology analysis demonstrated that numerous octahedral FeCoNi/C carbon frameworks were almost uniformly distributed on the wrinkled surfaces of flaky graphene. Moreover, the electromagnetic parameters and wave absorbing properties of obtained composites were regulated through simply changing the addition amounts of graphene oxide. Significantly, the as-prepared FeCoNi/C decorated graphene composite with the addition amount of graphene oxide of 67.2mg exhibited the best electromagnetic absorption performance. The minimum reflection loss was as large as -66dB at 15.6GHz and broad absorption bandwidth reached up to 4.8GHz with an ultrathin thickness of 1.53mm and a filler loading ratio of 30wt%. Furthermore, the maximum absorption bandwidth was enlarged to 5.2GHz via slightly adjusting the matching thickness to 1.56mm. Additionally, the probable electromagnetic attenuation mechanisms of attained composites were proposed. The results of this study would provide a reference for the preparation of MOF derived carbon-based magnetic composites as ultrathin and high-performance electromagnetic absorbers.

Electromagnetic Absorption and Mechanical Properties of Natural Rubber Composites Based on Conductive Carbon Black and Fe3O4.

In contemporary civilization, the electromagnetic radiation from electronic devices and communication systems has become a substantial pollutant. High-performance electromagnetic absorbers have become a solution for absorbing unwanted electromagnetic waves. This research proposed a lightweight and flexible electromagnetic absorber produced from natural rubber filled with conductive carbon black (CCB) and Fe3O4. The effect of CCB, Fe3O4, and a combination of CCB and Fe3O4 as a hybrid filler on foam morpholog, electromagnetic reflectivity, tensile strength, and compression set properties were investigated. In addition, the effect of the alternating layered structure of CCB and Fe3O4 on electromagnetic absorption was investigated. The results indicated that the composite foam exhibited an interconnected network structure that enhanced the electromagnetic attenuation in the absorber. CCB increased the electromagnetic absorption of the foam, whereas Fe3O4 had less of an effect. The foam filled with the hybrid filler at the CCB/Fe3O4 ratio of 8/2 exhibited excellent electromagnetic absorption. The composite foam had a higher tensile modulus and higher strength compared to neat foam. The addition of CCB decreased the compression set; however, the compression set was improved by the incorporation of Fe3O4. Composite foams filled with hybrid filler can serve as highly efficient electromagnetic absorbing materials.

An angle-insensitive electromagnetic absorber enabling a wideband absorption

· This work shows the relationship between the orientation of micro-/nanostructures of the EM absorbers and the associated EM parameters. · A mechanism to describe the underlying mechanism behind the EM incident angle sensitivity of the EM absorbers is proposed in this work. · The proposed mechanism guided the development of a novel class of EM absorbers with wide-angle, high-performance EM absorption. · A graphitized carbon nanospheres derived from bamboo exhibit angle-insensitive and wideband EM absorption performance with an effective absorption band up to 3.5 GHz under a thickness of 1.4 mm only. Electromagnetic (EM) wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves. However, designing an EM absorber with its performance capacity independent of the EM wave incident angle remains elusive to date. Resolving this challenge requires development of EM absorbers whose EM absorption performance is insensitive to the EM wave incident angle. Herein, we synthesized EM absorbers with a variety of structures with different symmetries (including micro-/nanospheres, nanoflakes and nanotubes) to study the effect of the EM absorbers' structure and the EM wave incident angle on the EM absorption performance. Our analysis reveals that non-magnetic EM absorbers with spatially symmetric nanostructures exhibit excellent EM wave incident angle-insensitivity. Finally, we demonstrate that a class of non-magnetic EM absorbers made from bamboo derived-carbon nanospheres exhibit EM incident angle-insensitivity and wideband EM absorption performance with an effective absorption band up to 3.5 GHz when the thickness is 1.4 mm, a significant improvement from prior studies which used thicknesses as high as 3–4 mm for comparable EM absorption performance.

Construction of ZnIn2S4 nanosheets/3D carbon heterostructure with Schottky contact for enhancing electromagnetic wave absorption performance

The construction of environment-adapted FCS@ZIS heterostructure with Schottky contact for enhancing EM absorbing property. • A novel heterostructure composed of ZnIn 2 S 4 /carbon is constructed as EM absorber. • The interfacial design with Schottky contact can promote the polarization effect. • The EM absorbing ability is optimized by tunning energy level and heterointerface. • The FCS@ZIS has application potential with excellent environmental adaptability. To alleviate the electromagnetic (EM) contamination, high-performance EM absorbers are urgently required. Constructing heterostructures with diverse energy level structures and high interfacial coupling effects has been considered as an ideal strategy to induce outstanding EM absorbing ability. In this work, the in-situ synthesis of interlaced ZnIn 2 S 4 (ZIS) nanosheets on the 3D foam-like carbon skeleton (FCS) using convenient carbonization and solvothermal approach is used to create a novel heterostructure with Schottky contact, which is then used as EM absorbers. By developing highly utilized heterointerfaces and different energy level structures, the FCS@ZIS heterostructure demonstrates a balanced synergy of multiple-attenuation mechanisms and impedance matching. With appropriate ZIS adjustment, the absorption bandwidth improves from 3.8 GHz to 4.3 GHz, and the lowest reflection coefficient is optimized from −15.6 dB to −52.7 dB, revealing the EM absorbing potential of FCS@ZIS. Furthermore, the unique nano-micro structure of FCS@ZIS can boost the matrix’s hydrophobic ability, which is quite significant in practical applications. The importance of the FCS@ZIS Schottky heterostructure in improving the EM absorbing property is revealed in this study, which also proposes a potential technique for developing outstanding EM absorbers.

Tailoring conductive network Zn@NPC@MWCNTs nanocomposites derived from ZIF-8 as high-performance electromagnetic absorber for the whole X-Band

A porous 3D cross-linked conductive network pierced by multi-wall carbon nanotubes (MWCNTs) was successfully designed from zeolitic imidazolate framework-8 (ZIF-8). Zn@NPC@MWCNTs composites were tailored by the facile regulating the mass ratios and thermal annealing treatment. Due to the combination of less eddy current loss and dielectric loss together with multiple reflection attenuation caused by a unique structure. With a 10 wt% filler loading, the Zn@NPC@MWCNTs composites carbonized at 800 °C show two high reflection loss (RL) values with different thicknesses. An RL value is −53.18 dB with 4.09 mm thickness in the C-Band (4–8 GHz), and a minimum RL can reach −74.83 dB (10.8 GHz) with a matching thickness of 2.749 mm. The effective absorption bandwidth is 4 GHz (from 8 to 12 GHz, RL ≤ −10 dB), which just covers the full X-band. Low cost and easy preparation can also provide advantages to develop MOF-based materials as effective EMW absorbents.

Nanocomposite synthesis of MoS2/nano-CeO2 for high-performance electromagnetic absorption

Nanocomposite synthesis of MoS2/nano-CeO2 for high-performance electromagnetic absorption

In-situ formation of low-dimensional, magnetic core-shell nanocrystal for electromagnetic dissipation

Rational design of low-dimensional, core-shell nanocrystals with superior synergistic dimensional-interfacial effect is promising to address the growing electromagnetic (EM) pollution challenge. Particularly, the monodispersed and core/shell component-controllable nanocrystal is highly desirable but remains challenging. Herein, a monodispersed core-shell nanocrystal consisting of a magnetic iron-based core and graphitized carbon (g-C) shell is synthesized via the in-situ pyrolysis of bamboo-derived lignin modified Fe3O4 (Fe3O4-lignin). The component of core can be controllably manipulated by altering the amount of lignin and a variety of iron-based cores, such as Fe3O4/Fe3C, Fe3C/Fe, Fe3O4/Fe3C/Fe and so forth, can be obtained using this in-situ pyrolysis approach. The result revealed that the optimized sub-13-nm-sized Fe–C nanocrystal displayed an ultra-wide EM absorption range (8.4–18.0 GHz) and the minimum reflection loss (RLmin) value was even reached as low as −47.11 dB at 8.0 GHz. The correlation of component-structure-dielectric or magnetic loss was further well investigated to reveal the EM dissipation mechanism. This novel method for sub-13-nm-sized magnetic nanocrystals is of great significance for the synthesis and design of nanocrystals and the mechanism study shed new sights for future high-performance electromagnetic absorbers.

Synthesis of ternary core-shell structured ZnOC@CoC@PAN for high-performance electromagnetic absorption

A novel ternary core-shell structured ZnOC@CoC@PAN as an electromagnetic wave (EMW) absorber was successfully fabricated by calcining precursor ZIF-8@ZIF-67 and covering the product with conductive polyaniline (PAN). The multicomponent core-shell structure and the conductive polymer coating were conducive to increasing the dielectric loss, magnetic loss, interfacial polarization, and conductivity loss to dissipate EMW energy. Adjusting the amount of aniline gave ZnOC@CoC@PAN-0.5, which had excellent EMW absorption performance. The minimum reflection loss ( RL min ) was −50.62 dB at 13.66 GHz and the effective absorption bandwidth (RL < −10 dB) reached 5.86 GHz with a matching thickness of 2.05 mm. This novel core-shell structured ZnOC@CoC@PAN has great potential in the field of EMW absorption. • ZnOC@CoC@PAN has a unique ternary shell structure, which can construct multiple interfaces to enhance interfacial polarization. • The RL min is −50.62 dB at 13.66 GHz and the effective absorption bandwidth is up to 5.86 GHz with the matching thickness of 2.05 mm. • The mechanism of absorption is explored from the microscopic perspective.

MOF−Guest complex derived Cu/C nanocomposites with multiple heterogeneous interfaces for excellent electromagnetic waves absorption

Electrical conductivity and interfacial polarization are two crucial factors to design high-performance electromagnetic absorption (EMA) materials, but how to synergistically balance these factors still remains to be difficult. In this work, we report the synthesis of Cu/C nanocomposites via the controlled pyrolysis of a MOF-guest complex. The prepared Cu/C nanocomposites are made up of cross-linked carbon network and various irregular particles. The carbon network provides appropriate electrical conductivity to contribute to the conductance loss. Multiple heterogeneous interfaces, such as Mo2C/C, Mo2C/CuO, CuO/C, Mo2C/Cu, and Cu/C interfaces, have been determined in these Cu/C nanocomposites, resulting in obviously improved polarization loss. As a result, the Cu/C nanocomposite exhibits excellent EMA performance, where the efficient absorption bandwidth reaches 6.8 GHz, and the maximal absorption gets to −52 dB. This research provides new idea to design high-performance EMA nanocomposites by tuning the electrical conductivity and interfacial polarization.

Rational construction of MXene/Ferrite@C hybrids with improved impedance matching for high-performance electromagnetic absorption applications

Sandwiched MXene/Ferrite@C (Ti3C2Tx/Fe3O4@C) hybrids have been successfully obtained by assembling MXene with Fe3O4@C nanoparticles derived from Fe-MOFs. The MXene/Ferrite@C hybrids achieved an excellent microwave absorption performance with a RLmin of −45.5 dB, an effective absorbing bandwidth of 3.5 GHz and a thin thickness of 1.6 mm. Therefore, the sandwiched MXene/Ferrite@C hybrids are expected to be powerful candidates for high performance electromagnetic microwave absorbers.

Fabrication of nitrogen-doped reduced graphene oxide/cobalt ferrite hybrid nanocomposites as broadband electromagnetic wave absorbers in both X and Ku bands

In this work, nitrogen-doped reduced graphene oxide decorated by magnetic cobalt ferrite (NRGO/CoFe2O4) hybrid nanocomposites were fabricated through solvothermal and hydrothermal two-step processes. Results of structure and micromorphology analysis manifested that numerous nanosized CoFe2O4 particles were uniformly anchored on the wrinkled surfaces of flake-like NRGO, and considerable nitrogen atoms had been doped into the crystal lattice of RGO. Moreover, the influences of additive amounts of CoFe2O4 and hybridization with NRGO on the electromagnetic parameters and absorption properties were carefully examined. Significantly, the as-synthesized nanocomposite with the content of NRGO of 13.76 wt% exhibited the optimal electromagnetic absorption capacity, i.e. the minimum reflection loss achieved −48.4 dB and broadest absorption bandwidth reached 6 GHz (12–18 GHz) under a small matching thickness of merely 1.9 mm and low filler content of 30 wt%. It should be mentioned that full absorption of both X and Ku bands was realized in the as-fabricated nanocomposites by facilely modulating the additive amounts of CoFe2O4 and matching thicknesses. Furthermore, the hybrid nanocomposites showed strong absorption intensity (≤ −20 dB, 99% absorption) in a wide thickness range of 1.9–5 mm. Besides, the potential electromagnetic absorption mechanisms were uncovered. Therefore, our results opened a novel idea for designing RGO-based dielectric/magnetic hybrid nanocomposites as high-performance electromagnetic absorbers.

Novel high-performance electromagnetic absorber based on Nitrogen/Boron co-doped reduced graphene oxide

In this work, N/B co-doped reduced graphene oxide were successfully synthesized with two-step hydrothermal self-assembled process, and exhibited excellent electromagnetic microwave absorption under a loading content of only 5 wt%. Its absorption bandwidth below −10 dB was 6 GHz at a thickness of 2.8 mm, and the minimum reflection loss was −52 dB. The nitrogen/boron co-doping mechanism and influences of multiple atomic bonding configurations on the absorbing properties were investigated in detail. The results suggested that various atomic bonding configurations, including C–N bonds (essentially for pyridinic N and pyrrolic N) with electron donor properties and C–N–B bonds with electron acceptor properties, played synergistic role in improving the electromagnetic absorption performance. The equivalent electric diploe composed of various atomic bonding configurations with electronic resonances, consumed the electromagnetic energy in the manner of “molecular” thermal vibration, and endowed the absorber with impedance matching and good electromagnetic attenuation ability.