Wide Effective Absorption Bandwidth Research Articles

Facile synthesis and excellent electromagnetic wave absorption properties of Air@RGO/CoNi hollow microspheres

The rational synergy of chemical composition and spatial nanostructures plays an important role in high-performance electromagnetic wave (EMW) absorption materials. Here, reduced graphene oxide (RGO) hollow microspheres loaded with CoNi alloy nanoparticles (Air@RGO/CoNi) were constructed by a facile water-in-oil emulsification route followed by high-temperature thermal treatment. The crystal structure, composition, microstructure, and magnetic properties of Air@RGO/CoNi were characterized by XRD, XPS, TEM, and VSM, respectively. The results demonstrated that the as-obtained Air@RGO/CoNi composites showed a uniform spherical morphology with a remarkably hollow structure. Impressively, nano-CoNi particles were compactly and uniformly distributed on the surface of RGO. Benefiting from the unique structure and compositional merits, the optimized Air@RGO/CoNi hollow microspheres exhibit superior (EMW) absorption performance. The minimum reflection loss (RLmin) value reached up to −56.16 dB at 13.67 GHz with a thin thickness of 2.55 mm and the widest effective absorption bandwidth (RL values are below −10 dB) covered 8.65 GHz (9.15–17.8 GHz) with a thinner thickness of 2.4 mm. Furthermore, possible EMW attenuation mechanisms had been proposed. Given these outstanding findings, we believe the as-fabricated Air@RGO/CoNi hollow microspheres can be promising candidates as highly microwave absorption materials with thin thickness, wide absorption bandwidth, and high absorption capacity.

Constructing hierarchical hollow flower-like MoO2/CoNi/NPC microspheres via water-in-oil system assisted supramolecular self-assembly for high-efficient electromagnetic wave absorption

Starting from the composition combination and structural design of materials, the novel high-efficiency absorber can be exploited. Herein, we constructed hollow flower-like MoO2/CoNi/NPC microspheres by virtue of supramolecular self-assembly in water-in-oil system and carbonization. The study found that when the mass ratio of the phosphomolybdic acid and dopamine hydrochloride was 3:4, and the oil phase solvent was glycol, microspheres presented outstanding electromagnetic wave (EMW) absorption performance. Its minimum reflection loss (RLmin) value was − 54 dB and the effective absorption bandwidth (EAB) was 4.72 GHz at 1.97 mm with the filling ratio of 35 wt%. When the thickness was only 1.7 mm, the widest EAB was up to 6.48 GHz (11.52–18 GHz), covering the entire Ku-band. The excellent EMW absorption performance was mainly attributed to the multiple scattering and enhanced impedance matching caused by the 3D flower-like hollow structure, as well as the strong polarization loss induced by the double-layer structure and Schottky contact. We also utilized the radar cross section (RCS) analysis method to simulate and calculate electromagnetic (EM) scattering performance of aluminum metal plates with absorbing coatings. The analysis results further manifested that MoO2/CoNi/NPC could be used as excellent absorber.

Ambient-drying to construct unidirectional cellulose nanofibers/ carbon nanotubes aerogel with ultra-lightweight, robust, and superior microwave absorption performance

Microwave absorption materials (MAMs) with lightweight wide effective absorption band, superb mechanical performance, and capable of large-scale preparation are highly desirable for dealing with microwave pollution, but it is still a challenge to realize these performances simultaneously on one material. Herein, we report an ambient drying and non-chemical cross-linking way of preparing high-performance microwave absorption aerogels from cellulose nanofibers (CNF) and carbon nanotubes (CNT). Anisotropic aerogel pore walls with excellent mechanical properties can be constructed by unidirectional cycling freeze-thaw to cross-linking CNF and CNT. During this process, a sustainable bioinspired dual-networks interpenetrating strategy is constructed by benefiting from the mono-dispersion of CNF and CNT, thus enabling the creation of hybrid dual-networks of hydrophobic/hydrophilic nanofibers. Impressively, it is found that the dual-networks induced anisotropic aerogel structure and dense pore walls can synergistically result in favorable mechanical properties. In detail, aerogels with tunable ultralow densities (0.0262–0.0296 g cm−3), high mechanical properties (the stress of the sample reaches up to 329.8 kPa at 75% strain) and low shrinkage (∼10%) can be prepared. Besides, the aerogels behave a large-scale production future (diameter of aerogel up to 9.24 cm). The as-prepared aerogel delivers a remarkable minimal reflection loss (RLmin) of −60.22 dB at 13.012 GHz and a wide effective absorption bandwidth (EAB) from 2.163 to 18 GHz (15.84 GHz) at a thin thickness of 7.46 mm, which covers almost all the S, C, X, and Ku bands. This work provides a strategy to prepare lightweight and efficient microwave absorbers, as well as illustrates good impedance matching and moderate dielectric loss capability.

Scalable preparation of SiC@SiO2 nanocable aerogels for broadband microwave absorption using low-cost carbon source

Despite significant efforts, microwave contamination has become increasingly common and difficult to address. Given this complication, SiC nanowire aerogels emerge as promising candidates for microwave absorbers due to their hybridized ceramic-electromagnetic properties, ultra-low density, and high porosity. However, conventional methods for preparing SiC nanowires heavily rely on reaction equipment and protective gases, as well as expensive or toxic raw materials. Therefore, we present a facile, catalyst-free, and cost-effective method for synthesizing ultralight and elastic SiC@SiO2 nanocable aerogels (SNCA) using a low-cost carbon source. With a unique three-dimensional assembly structure, the as-prepared SNCA exhibits a significant compressive-recovered property, which is rare in ceramic materials. Moreover, the optimized SNCA demonstrates a wide effective absorption bandwidth (10.2 GHz) and strong reflection loss (−56.6 dB) for microwave absorption applications, with the attenuation mechanism primarily attributed to multiple reflections, interface polarization, and dipole polarization. These findings suggest that SiC nanofiber aerogels synthesized using this low-cost general method hold immense potential for next-generation microwave absorbing devices in extreme environments.

Design and synthesis of graphene-like porous grapefruit peel/Ni0.5Co0.5Fe2O4 composite with high-performance microwave absorption

The rapid developments in communication technology and aerospace have prompted the renewal of electromagnetic wave (EMW) materials. Here, we have prepared graphene-like porous grapefruit peel/Ni0.5Co0.5Fe2O4 composite by in-situ generation. The graphene-like porous structure improves conductive loss and multi-polarization availably. Meanwhile, the addition of Ni0.5Co0.5Fe2O4 facilitates to introduce the magnetic loss. Moreover, the large number of pores promotes multiple reflections and scattering of EMW, thus improving EMW absorption performance. Through adjusting the carbonization temperature, the sample with extremely thin thicknesses (1.7 mm) achieves wide effective absorption bandwidth (5.14 GHz). It offers a path to the practical application of new absorbing materials with wider absorption bands and thin thickness.

Designing flower-like MOFs-derived N-doped carbon nanotubes encapsulated magnetic NiCo composites with multi-heterointerfaces for efficient electromagnetic wave absorption

In order to acquire exceptional electromagnetic wave absorption properties, the microstructure design and component modification of composites are essential. Metal-organic frameworks (MOFs), due to the unique metal–organic crystalline coordination, tunable morphology, high surface area, and well-defined pores, have been regarded as promising electromagnetic wave absorption materials precursors. However, the inadequate contact abilities between adjacent MOFs nanoparticles endow it with undesirable electromagnetic wave dissipation capacity at a low filler loading, which is a great challenge to break size effect of nanoparticles to achieve efficient absorption. Herein, NiCo-MOFs derived N-doped carbon nanotubes encapsulated with NiCo nanoparticles anchored on flowers-like composites (denoted as NCNT/NiCo/C) were successfully prepared through facile hydrothermal method followed by thermal chemical vapor deposition with melamine-assisted catalyst. By controlling the Ni/Co ratio in precursor, the tunable morphology and microstructure of MOFs are achieved. Most importantly, the derived N-doped carbon nanotubes tightly connect the adjacent nanosheets to construct the special 3D interconnected conductive network, which effectively accelerates the charge transfer and improves the conduction loss. And notably, the NCNT/NiCo/C composite delivers excellent electromagnetic wave absorption performance with minimum reflection loss of −66.1 dB and wide effective absorption bandwidth up to 4.64 GHz when the Ni/Co ratio is 1:1. This work provides a novel method for the preparation of morphology controllable MOFs-derived composites and realizes high-performance electromagnetic wave absorption properties.

Enhanced electromagnetic wave absorption of nitrogen-doped reduced graphene oxide aerogels with LaFeO3 cluster modifications

Today, electromagnetic wave (EMW) absorbing materials with strong absorption capacity alone are hardly enough to meet the growing problem of EMW pollution. This work is the first designs and synthesizes LaFeO3-decorated nitrogen (N)-doped reduced graphene oxide aerogel (LFO/N-rGO) novel composites by a simple hydrothermal method. When the mass ratio of the LaFeO3 (LFO) nanoparticles: graphene oxide (GO): urea is 1:5:7.5, LFO/N-rGO achieves broadband absorption while possessing strong electromagnetic wave absorption capability. A strong reflection loss (RL) of −64.5 dB is obtained at 9.2 GHz. In addition, the maximum effective absorption bandwidth with a 2.83 mm thickness can reach up to 6.72 GHz. The EMW absorption mechanism analysis shows that the excellent microwave absorption capability is mainly attributed to the enhanced multiple reflections and multi-scattering, enhanced interfacial polarization process, proper conduction loss, and optimized impedance matching characteristics. Herein, this work proposes a new approach to improve the microwave absorption capability of N-doped reduced graphene oxide-based composites and provides a novel strategy to design EMW absorbing materials with wide effective absorption bandwidth and strong absorption capacity.

In Situ Grown 1D/2D Structure of Dy3Si2C2 on SiCw for Enhanced Electromagnetic Wave Absorption

To improve electromagnetic wave (EMW) absorption performance, a novel nano-laminated Dy3Si2C2 coating was successfully in situ coated on the surface of SiC whisker (SiCw/Dy3Si2C2) using a molten salt approach. A labyrinthine three-dimensional (3D) net was constructed by the one-dimensional (1D) SiCw coated with the two-dimensional (2D) Dy3Si2C2 layer with a thickness of ~100 nm, which significantly improved the EMW absorption properties of SiCw. Compared to pure SiCw with the minimum reflection loss (RLmin) value of -10.64 dB and the effective absorption bandwidth (EAB) of 1.04 GHz for the sample with a thickness of 4.5 mm, SiCw/Dy3Si2C2 showed a significantly better EMW absorption performance with RLmin of -32.09 dB and wider EAB of 3.76 GHz for thinner samples with a thickness of 1.76 mm. The enhancement of the EMW absorption performance could be ascribed to the improvement of impedance matching, enhanced conductance loss, interfacial polarization as well as multiple scattering. The SiCw/Dy3Si2C2 can be a candidate for EMW absorber applications due to its excellent EMW absorption performance and wide EAB for relatively thin samples, light weight, as well as potential oxidation and corrosion resistance at high temperatures.

Grain boundary capacitance effect in Iron-based magnetic composites for superior C-band microwave absorption

Urgently, the absorbing bandwidth of magnetic materials is enormously limited in C-band by the exorbitant magnetic response. There are few reports about C-band absorber. In this paper, iron-based magnetic composites with large-angle grain boundaries (120°) were prepared by gelatinized starch assisted separation nucleation and solid phase sintering. Noteworthily, grain boundary capacitance layer is formed at the grain boundaries, effectively enhancing its dielectric parameters. This is facilitated to achieve balanced impedance matching. Therefore, the effective absorption bandwidth (EAB) of FFC-B covered the whole C-band (4–8 GHz). Natural resonance and impedance matching realized by grain boundary capacitance effect were confirmed to be the key to such wide EAB for FFC-B in C-band. This work explores the important role of grain boundary capacitance effect in regulating the dielectric parameters of iron-based magnetic materials, and provides a feasible strategy of grain boundary engineering for the low-frequency and wide EAB electromagnetic performance.

Structural and phase reconfiguration induced electromagnetic wave absorption of g-C3N4 bridging Co@NC and Fe3C@NC

Developing electromagnetic wave (EMW) absorbers with low-cost, lightweight, strong absorption capacity, thin matching thickness, and wide effective absorption bandwidth (EAB) is still a significant challenge. Herein, we report a unique g-C3N4/Fe3CNC/Co-NC heterostructure by simple mixing and two-step pyrolysis of melamine, Fe3O4, and ZIF-67. After the structural and phase reconfiguration, N-doped carbon layer-coated Fe3C nanoparticles (NPs) assembled nanoshells (Fe3C@NC) and N-doped graphitic carbon-coated metallic Co NPs (Co@NC) are formed, and the core-shell NPs are interconnected by porous g-C3N4 bridges. Profiting from the successful construction of the unique g-C3N4/Fe3CNC/Co-NC heterostructure and the synergetic effect of multi-component, multiple core-shell structure, and strong interaction, the as-fabricated g-C3N4/Fe3CNC/Co-NC inherits the excellent EMW absorption performance with a RL value of -25.4 dB at a thin matching thickness of 2.6 mm. The EAB can reach up to 8.64 GHz at a thickness of 2∼5 mm. This study provides the contribution of structural and phase reorganization to the field of EMW absorption.

Thermal stability of Ni3ZnC0.7: As tunable additive for biomass-derived carbon sheet composites with efficient microwave absorption

With the rapidly development of radar detection technology and the increasingly complex application environment in military field and electromagnetic pollution surrounded by electron devices, increasingly demand is needed for electromagnetic wave absorbent materials with high absorption efficiency and thermal stability. Herein, a novel Ni3ZnC0.7/Ni loaded puffed-rice derived carbon (RNZC) composites are successfully prepared by vacuum filtration of metal-organic frameworks gel precursor together with layered porous-structure carbon and followed by calcination. The Ni3ZnC0.7 particles uniformly decorate on the surface and pores of puffed-rice derived carbon. The puffed-rice derived carbon@Ni3ZnC0.7/Ni-400 mg (RNZC-4) sample displayed the best electromagnetic wave absorption (EMA) performances among the samples with different Ni3ZnC0.7 loading. The minimum reflection loss (RLmin) of the RNZC-4 composite reaches −39.9 dB at 8.6 GHz, while widest effective absorption bandwidth (EAB) of RNZC-4 for RL < −10 dB can reach 9.9 GHz (8.1–18 GHz, 1.49 mm). High porosity and large specific surface area promote the multiple reflection-absorption effect of the incident electromagnetic waves. The Ni3ZnC0.7 nanoparticles provide a large number of interfaces and dipole factors. Analysis reveals that the RNZC-4 remained general stability under 400 °C with formation of a small amount of NiO and ZnO phases. Surprisingly, at such high temperature, the absorbing properties of the material are improved rather than decreased. Obviously, the material still maintains good electromagnetic wave performance at high temperature, and implies that the absorber shows good performance stability. Therefore, our preparations exhibit potential applications under extreme conditions and a new insight for the design and application of bimetallic carbides.

Core–shell Ni3Sn2@C particles anchored on 3D N-doped porous carbon skeleton for modulated electromagnetic wave absorption

Synthesizing multi-component composites via a straightforward, reliable, and scalable approach has been challenging. Herein, a three-dimensional nitrogen-doped porous carbon decorated with core–shell Ni3Sn2@carbon particles (3D N-PC/Ni3Sn2@C) was customized through a simple salt-template pyrolysis approach. The formed Ni3Sn2 particles are perfectly surrounded by crystalline carbon layers and embedded in 3D carbon walls during pyrolysis. The dual protection of crystalline carbon layers and porous carbon walls guarantees the electrical conductivity and stability of Ni3Sn2. The intriguing 3D and core–shell structure coupled with the introduction of multiple components empowers the composite with rich heterogeneous interface and conductive network, and contributes to the lightweight, corrosion resistance, oxidation resistance, and superior stability of electromagnetic (EM) wave absorbers. The N-PC/Ni3Sn2@C possesses the minimum reflection loss (RLmin) of –54.01 dB and wide effective absorption bandwidth (EAB) of 7.36 GHz under a low filler content of less than 10%. The concept in the work proposes a facile, eco-friendly, and scalable pathway for the synthesis of other heterogeneous structures of EM wave absorbers.

Extended effective absorption bandwidth of Sendust/phosphate flaky particles by TiO2 insulation coating

How to obtain a wide effective absorption bandwidth is still a challenge for Sendust micro-powder as microwave absorber at 2–10 GHz range. Double shell-core structured composites are desirable to extend effective absorption bandwidth through optimizing impedance match degree in wider frequency and forming a broad dielectric loss peak. In this work, TiO2 layer is fabricated on surface of flaky Sendust/phosphate composites through the hydrolysis reaction for constructing double shell-core structured TiO2@phosphate@Sendust flaky composites. The synergistic effect of TiO2-phosphate interface and phosphate-Sendust interface induces a broad peak for dielectric loss, microwave absorption ratio and attenuation constant, resulting in wider effective absorption bandwidth of 3.2 GHz compared with that (2.4 GHz) of raw Sendust/phosphate composites. This work offers a facile and effective strategy for extending effective absorption bandwidth of micron-scale microwave absorber.

Facile fabrication of Co-MOF/GNs derivatives as electromagnetic wave absorber with thin thickness for X and Ku bands

The application of carbon matrix and magnetic composites as electromagnetic wave absorbing materials has attracted extensive attention. The Co-MOF/Graphite nanoflakes (GNs) derived microwave absorbing material supported by MOF structure was acquired via hydrothermal method and subsequent calcination treatment. The best reflection loss value of the sample obtained by pyrolysis at 600 °C is −43.62 dB at 15.84 GHz, simultaneously, the thickness is only 1.6 mm, and the effective absorption bandwidth (EAB) can reach 5.2 GHz (12.8–18 GHz). The Co-MOF/GNs derivatives possess a thinner absorbent thickness and a rather wide EAB value (mainly distributed in the X and Ku bands). Its absorbing bandwidth and thickness of absorbing agent are far superior to most MOF-derived absorbing materials. Its excellent electromagnetic wave absorption performance is chiefly attributed to multi-component dipole polarization, interface polarization from multiple interfaces, and multiple reflection and scattering effects of sandwich micro-structure with high porosity on electromagnetic waves. This paper provides a certain reference value for the design of lightweight and efficient radar absorbers suitable for X and KU bands, which can be applied to radar absorbing materials, multi-band and various applications.

Combinatorial Structural Engineering of Multichannel Hierarchical Hollow Microspheres Assembled from Centripetal Fe/C Nanosheets to Achieve Effective Integration of Sound Absorption and Microwave Absorption.

Electromagnetic radiation and noise pollution are two of the four major environmental pollution sources. Although various materials with excellent microwave absorption performances or sound absorption properties have been manufactured, it is still a great challenge to design materials with both microwave absorption and sound absorption abilities due to different energy consumption mechanisms. Herein, a combination strategy based on structural engineering was proposed to develop bi-functional hierarchical Fe/C hollow microspheres composed of centripetal Fe/C nanosheets. Both of the interconnected channels created by multiple gaps among the adjacent Fe/C nanosheets and the hollow structure have positive effects on the absorbing performances by promoting the penetration of microwaves and acoustic waves and prolonging action time between microwave energy and acoustic energy with materials. In addition, a polymer-protection strategy and a high-temperature reduction process were applied to keep this unique morphology and further improve the performances of the composite. As a result, the optimized hierarchical Fe/C-500 hollow composite exhibits a wide effective absorption bandwidth of 7.52 GHz (10.48-18.00 GHz) at only 1.75 mm. Furthermore, the Fe/C-500 composite can effectively absorb sound wave in the frequency of 1209-3307 Hz, basically including part of the low frequency range (<2000 Hz) and most of the medium frequency range (2000-3500 Hz), and has 90% absorption of sound at 1721-1962 Hz. This work puts new insight into the engineering and development of microwave absorption-sound absorption-integrated functional materials with promising applications.

Engineering core–shell heterocomposites of integrated 0D ZIF-8 (Zn) attached on 1D MIL-68 (In) nanorods for high performance electromagnetic wave absorption

With the booming development and wide applications of smart and portable devices, electromagnetic wave (EMW) pollution and radiation are attracting more and more attention. EMW absorption materials play a vital role in solving the above problems. It is a still challenge to simultaneously realize strong reflection loss (RL), broad effective absorption bandwidth and lightweight of EMW absorption materials. In this paper, ZnO/C@In/C core–shell porous carbon hetero-rods were designed and synthesized via the pyrolysis of double MOFs with core–shell structure (MIL-68 (In) nanorods coated by ZIF-8 (Zn) dodecahedron nanoparticles). The ratio of MIL-68 (In) and ZIF-8 (Zn) in ZnO/C@In/C heterostructure composite was adjusted to achieve the impedance matching, resulting in most EMW entering composites. ZnO/C@In/C-0.136 exhibits a minimum RL of −56.75 dB at 16.34 GHz and broad effective absorption bandwidth of 6.76 GHz under the thickness of 2.36 mm, which is due to the impedance matching and high attenuation ability coming from a large number of interfaces. The finding of this study not only provides a facile preparation method of porous carbon with core–shell structure, but also offers a strategy for achieving strong RL and wide effective absorption bandwidth via synergistic effect of dielectric loss and impedance matching.

Ultra-Light Nanocomposite Absorbers of Prussian Blue Analogue/Ni Nanocubes Decorated Reduced Graphene Oxide for Tunable Dielectric Properties and Microwave Absorption

Microwave absorbers with the Prussian blue analogue (PBA)/Ni nanocubes decorated reduced graphene oxide (RGO) nanosheet nanocomposites were fabricated by a one-step hydrothermal reduction method, aiming to investigate the effect of weak/strong polar assembly on the dielectric properties, impedance, and microwave absorbing performance in 1–18 GHz. By varying the ratio of PBA/Ni nanocube and RGO, the nanocomposites exhibit the tunable permittivity in a wide range through the modulation of the distributing density of the weak polar PBA nanocubes on the strong polar RGO nanosheets. Based on the magnetic attenuation supported by Ni on the PBA, the calculated impedance and reflection loss (RL) imply the tunable microwave absorbing properties and bandwidth in the C-Ku band. Using the suitable nanocube/RGO ratio, the minimum RL of the nanocomposites can achieve −43.5 dB at 2.2 GHz of the S band with an absorber thickness of 9.7 mm, while the widest effective absorption bandwidth (RL < −10 dB) arrived 5.0 GHz in the Ku band with a much thinner thickness of 1.9 mm. This work provides a simple design for the lightweight tunable MOF-based microwave absorbers.

Electrostatic self-assembly of Ti3C2Tx/Fe nanochain hybrids for efficient microwave absorber

It becomes more and more important to develop high-performance microwave absorbers and solve the problem of electromagnetic wave pollution. However, design of the microwave absorbers with wider effective absorption bandwidth and less filler loading still faces serious challenges. In this work, Ti3C2Tx nanosheets modified by Fe nanochain were prepared by the facile electrostatic self-assembly method. The Ti3C2Tx/Fe nanochain (Ti3C2Tx/Fe NCs-2) hybrids exhibit remarkable microwave absorption properties with the optimal reflection loss of −38.8 dB by thickness of 1.9mm. The effective absorption bandwidth reaches 6.72 GHz with the filler loading of 15 wt%. Furthermore, the radar cross-section reduction performance for hybrids has been proved by using computer simulation technology. When theta is at 0◦, the Ti3C2Tx/Fe NCs-2 shows the optimal radar cross-section reduction value of 19.43 dB. These results suggest that the Ti3C2Tx/Fe nanochain hybrid is a superior microwave absorber for practical applications.

Fabrication of a flexible and efficient electromagnetic wave absorber based on reduced graphene oxide/Fe7Co3 filled into polydimethylsiloxane

A flexible and efficient reduced graphene oxide/Fe7Co3/polydimethylsiloxane (rGO/Fe7Co3/PDMS) composite electromagnetic wave (EMW) absorber was prepared by a fast and simple liquid reduction and subsequent liquid phase blend method. The introduction of rGO tunes the dielectric constant and dielectric loss of the composite absorber, and Fe7Co3 imparts magnetic loss characteristics to the material. The rheological properties of PDMS enable rGO/Fe7Co3 to be well dispersed within it, forming a homogeneous structure, which contributes to the synergistic effect of the components and improves the impedance matching conditions and attenuation capability of the composite absorber. It is worth noting that the EMW absorption properties of the composites can be effectively adjusted by changing the amount of rGO/Fe7Co3 added to the PDMS. When the amount of rGO/Fe7Co3 is 8.00 wt%, rGO/Fe7Co3/PDMS-8 shows superior EMW absorption property. The minimum reflection loss (RLmin) of − 52.58 dB at 1.80 mm, and the widest effective absorption bandwidth (EAB, RL≤−10 dB) can reach 6.40 GHz (11.40–18.00 GHz) at only 1.60 mm. Furthermore, the twist test shows that the RLmin and widest EAB of rGO/Fe7Co3/PDMS-8 remained at 92.64 % and 97.50 % of its initial values after 1500 twists, respectively, demonstrating its excellent flexibility. These results indicate that such rGO/Fe7Co3/PDMS-8 composite is very promising as a next generation flexible and efficient EMW absorbing material.

RGO supported bimetallic MOFs-derived Co/MnO/porous carbon composite toward broadband electromagnetic wave absorption

The metal-organic frameworks-derived carbon-based electromagnetic wave (EMW) absorbing (EMWA) materials have attracted extensive attention. However, it still maintains a challenge to design the kind of materials with wide effective absorption bandwidth (EAB). Herein, a series of reduced graphene oxide (RGO) supported symmetrical lotus-like cobalt/manganese oxide/porous carbon (Co/MnO/PC/RGO) composites were synthesized by hydrothermal method and subsequent carbonization process. Impressively, the symmetrical porous structure and the special component could synergistically improve EMWA capacity. On the one hand, the symmetrical porous structure and magnetic component could optimize impedance matching, which were conducive to more EMW entering into the sample. On the other hand, the abundant heterointerfaces enhanced the interface polarization and the EMWA performance of the sample could be also regulated by the change of GO content in the mixture. When the GO content was 9 wt%, a minimum reflection loss value of −50.1 dB and the corresponding EAB value of 5.1 GHz (11.9–17.0 GHz) was achieved at a thickness of 2.0 mm. The excellent EMW performance of the sample stemmed from the increased dielectric loss and magnetic loss as well as improved impedance matching. As a consequence, this work authenticated a novel pathway to construct the carbon-based EMW absorbers with broad EAB.