Wave Absorption Materials Research Articles

Magnetic NiFe2O4@FeNi3 core-shell nanospheres derived from FeNi-LDH precursor anchoring on rGO nanosheets for enhanced electromagnetic wave absorption

Graphene has been extensively utilized in the domain of electromagnetic wave (EMW) absorption materials because of its excellent electrical conductivity. However, the inferior impedance matching performance and the single loss mechanism vastly restrict the application. Hence, it's an effective strategy to solve these issues by introducing magnetic components. Notably, layer double hydroxide (LDH) is an appropriate template to obtain magnetic component materials. Considering that ferromagnetic metals such as Fe, Co, Ni, and their corresponding metal oxides are usually treated as magnetic components which are promising candidates for EMW absorption materials. Therefore, in this work, a FeNi-layered double hydroxide-reduced graphene oxide (FeNi-LDH-rGO) aerogel was synthesized through a series of processes such as electrostatic self-assembly, hydrothermal, freeze-drying, and annealing. The magnetic NiFe2O4@FeNi3 core-shell nanospheres were obtained from FeNi-LDH precursor, anchoring on rGO nanosheets after the annealing treatment. Furthermore, the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption property and impedance matching performance were explored. As a consequence, the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth (EAB) of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt% and a low density of 4.4 mg/cm3. In conclusion, the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe2O4@FeNi3 core-shell structure nanospheres.

Carbon–ceramic nanofiber embedded with LDHs-derived composites for enhanced electromagnetic wave absorption

Hydrotalcite-like layered double hydroxides (LDHs) exhibit distinct microstructures and atomic compositions, and thus, they are expected to be superior microwave absorbing materials. However, preparation of excellent absorbers from LDHs is still a challenging task. Herein, NiCo-LDHs@SiC/C heterostructure composites were designed and then heat-treated to obtain NiCo@SiC/C nanofibers. Finally, with a synergistic effect of dielectric and magnetic losses, the minimum reflection loss value of the sample could reach −56.3 dB with a thickness of 2.7 mm, and the maximum effective bandwidth absorption reached 6.8 GHz at 2.3 mm. Moreover, the simulated radar cross-section indicates that the NiCo@SiC/C nanofibers well suppress the electromagnetic scattering from metal trench structure. This result further indicates the outstanding microwave absorption properties of the nanofibers. This study contributes to the development of LDH materials in the field of wave-absorbing materials, and is an important guideline for exploring efficient microwave absorbers with fibrous structure.

Anion-substitution interfacial engineering to construct C@MoS2 hierarchical nanocomposites for broadband electromagnetic wave absorption

Developing an effective strategy to regulate the interfacial properties of hierarchical structure is of great significance for preparation of high-performance electromagnetic wave absorption (EMA) materials. Ion-substitution can change intrinsic structure and properties of a materials, but its effect on the interfacial properties of hierarchical structure remained to be explored. Herein, we first constructed a C@MoS2 hierarchical structure via simple hydrothermal reaction, then used the ion-substitution strategy to replace the S atoms in MoS2 with O, F and Se, and finally obtained anion-substituted hierarchical structure (C@X-MoS2, X = O, F, Se). The results show that ion-substitution destroys the MoS2 crystal structure and realizes tunable dielectric properties of C@MoS2, which leads to further enhancement of overall interfacial polarization. After optimization, the absorption strength and width of C@O-MoS2 has been significantly improved. The minimum reflection loss (RLmin) reaches −62.17 dB, and the maximum effective absorption bandwidth (EABmax) is 7.0 GHz. The simulation results show the obtained absorbent can greatly reduce the radar cross section of target, indicating it has broad application potential. Therefore, this work provides a novel method for regulation of EMA performance of hierarchical structure and preparation of high-performance absorbents.

Interfacial covalent bonding of Ni doped MoS2/TiO2/Ti3C2Tx composites for electromagnetic wave absorption performance

Two-dimensional MXene and its composites are among the most attractive electromagnetic wave absorption (EMA) materials due to their unique structure. While previous studies have investigated 2D/2D MoS2/Ti3C2Tx heterojunctions for EMA, there is still a need for further adjustments to interface structure to enhance polarized electron density and electron transfer capacity. In this study, Cl-Ti3C2Tx was prepared by Lewis acid molten salt etching of Ti3AlC2, and S-Ti3C2Tx was prepared by replacing Cl with S. MoS2 nanosheets were grown on the surface of S-Ti3C2Tx by a simple hydrothermal method, forming a Ti-S-Mo covalent interface. The EMA properties of the composites were further optimized by adjusting the interface oriented polarization and electronic structure through Ni doping. Compared to MoS2/TiO2/Ti3C2Tx, the electromagnetic wave absorption performance of Ni-MoS2/TiO2/Ti3C2Tx had been significantly improved. When the Ni doping amount was 0.086 mmol, the minimum reflection loss of Ni-MoS2/TiO2/Ti3C2Tx could reach −48.04 dB at 8.64 GHz, with an effective absorption bandwidth of 3.28 GHz. This study provides theoretical basis and experimental evidence for the follow-up research of MXene-based composite EMA materials.

Ultrafine Vacancy-Rich Nb2O5 Semiconductors Confined in Carbon Nanosheets Boost Dielectric Polarization for High-Attenuation Microwave Absorption

The integration of nano-semiconductors into electromagnetic wave absorption materials is a highly desirable strategy for intensifying dielectric polarization loss; achieving high-attenuation microwave absorption and realizing in-depth comprehension of dielectric loss mechanisms remain challenges. Herein, ultrafine oxygen vacancy-rich Nb2O5 semiconductors are confined in carbon nanosheets (ov-Nb2O5/CNS) to boost dielectric polarization and achieve high attenuation. The polarization relaxation, electromagnetic response, and impedance matching of the ov-Nb2O5/CNS are significantly facilitated by the Nb2O5 semiconductors with rich oxygen vacancies, which consequently realizes an extremely high attenuation performance of − 80.8 dB (> 99.999999% wave absorption) at 2.76 mm. As a dielectric polarization center, abundant Nb2O5–carbon heterointerfaces can intensify interfacial polarization loss to strengthen dielectric polarization, and the presence of oxygen vacancies endows Nb2O5 semiconductors with abundant charge separation sites to reinforce electric dipole polarization. Moreover, the three-dimensional reconstruction of the absorber using microcomputer tomography technology provides insight into the intensification of the unique lamellar morphology regarding multiple reflection and scattering dissipation characteristics. Additionally, ov-Nb2O5/CNS demonstrates excellent application potential by curing into a microwave-absorbing, machinable, and heat-dissipating plate. This work provides insight into the dielectric polarization loss mechanisms of nano-semiconductor/carbon composites and inspires the design of high-performance microwave absorption materials.

Metal-oxide doping enhances electromagnetic wave absorption performance of BaFe12O19 glass-ceramics

Elimination or reduction of electromagnetic wave pollution is receiving increasing attention; development of high-performance wave-absorbing materials has become key to solving this problem. In this study, BaFe12O19 crystals were precipitated in a BaO–Fe2O3–B2O3–SiO2 glass system using the melt-quench-second heat treatment method. The microstructure and magnetic properties of the BaFe12O19 glass ceramics and their electromagnetic wave loss characteristics were analyzed. The composition of the crystals in the glass can be modified by introducing other metal oxides, such as ZrO2 (BFO-Z), TiO2 (BFO-T), and Al2O3 (BFO-A), to enrich the heterogeneous interfaces and increase the dielectric loss of the material. The maximum effective absorption bandwidth of BaFe12O19 glass-ceramics with addition of ZrO2 (BFO-Z) was increased to 3.20 GHz; the minimum reflection loss was reduced to −45.60 dB. This simple method represents a new direction for fabricating high-performance wave-absorbing materials.

Rational construction of mushroom-like Ni@N-doped carbon tubes composites with enhanced electromagnetic wave absorption

It is confirmed that electromagnetic wave absorption (EMA) materials with a metal-carbon dual-phase structure has exposed great potential for achieving tunable, strong, and wide EMA. Herein, the mushroom-like Ni@N-doped carbon tubes (NNCTs) are prepared by nickel-catalyzed growth of carbon tubes, realizing carbon encapsulated metal particles. One end of the carbon tube grows and connects to form a bundle of mushroom-like structures, and the other end of the carbon tube is filled with nickel as the mushroom head. The structure control of NNCTs can be achieved by adjusting the amount of catalyst Ni. Appropriate amount of nickel can control the formation of mushroom-like structure. The results show that the structure has a great influence on the EMA performance. Particularly, NNCT-0.5 provides a minimum reflection loss of -60.47 dB with a thickness of 4.0 mm, and the widest effective absorption bandwidth for RL< -10 dB of NNCT-1.5 at a thickness of 2.00 mm was 7.53 GHz (10.47–18.00 GHz). The immobilization of carbon in melamine was achieved by catalytic generation of carbon tubes with metal ions Ni. Metal-carbon biphasic composites introduce dielectric and magnetic losses. The presence of multiple interfaces and voids in the mushroom structure allows tuning the dielectric parameters and optimizing the impedance matching. This work provides an effective strategy for the fabrication of dielectric and magnetic composites with special structures, which has great potential in attenuating electromagnetic wave energy.

Sodium chloride assisted synthesis of porous magnetic carbon nanocomposites containing cobalt nanoparticles for high-performance electromagnetic wave-absorption

High-performance electromagnetic wave-absorbing materials have attracted much attention owing to their wide application in military stealth, camouflage, and electromagnetic protection. Carbon materials have more advantages in achieving the performance goals of thin, light, wide, and strong absorption. The combination of ferromagnetic components is commonly used to further improve the absorption ability of carbon materials. Herein, porous Co/C nanocomposites attached with different Co content were prepared through the sodium chloride assisted carbonization process of glucose precursor containing cobalt salts. Dipole polarizations and dielectric relaxation in the carbon matrix, as well as interfacial polarizations at the heterogeneous interfaces collectively contributed to the total dielectric loss. Meanwhile, the existence of Co nanoparticles effectively improved the magnetic properties and increased magnetic loss. In addition, the impedance matching performance was also improved. As a result, the prepared Co/C nanocomposites achieved an absorption bandwidth of nearly 6 GHz, covering almost the whole Ku band from 12.1 to 18.0 GHz. And the minimum reflection loss exceeded −60 dB. This work provided a simpler and more effective approach to prepare high-performance absorbing materials.

Preparation and characterization of bifunctional wolfsbane-like magnetic Fe3O4 nanoparticles-decorated lignin-based carbon nanofibers composites for electromagnetic wave absorption and electrochemical energy storage

Recently, with the pursuit of high-efficiency electromagnetic wave absorption (EMWA) and electrochemical energy storage (EES) materials, multifunctional lignin-based composites have attracted significant interest due to their low cost, vast availability, and sustainability. In this work, lignin-based carbon nanofibers (LCNFs) was first prepared by electrospinning, pre-oxidation and carbonization processes. Then, different content of magnetic Fe3O4 nanoparticles were deposited on the surface of LCNFs via the facile hydrothermal way to produce a series of bifunctional wolfsbane-like LCNFs/Fe3O4 composites. Among them, the synthesized optimal sample (using 12 mmol of FeCl3·6H2O named as LCNFs/Fe3O4–2) displayed excellent EMWA ability. When the minimum reflection loss (RL) value achieved −44.98 dB at 6.01 GHz with an thickness of 1.5 mm, and the effective absorption bandwidth (EAB) was up to 4.19 GHz ranging from 5.10 to 7.21 GHz. For supercapacitor electrode, the highest specific capacitance of LCNFs/Fe3O4–2 reached 538.7 F/g at the current density of 1 A/g, and the capacitance retention remained at 80.3 %. Moreover, an electric double layer capacitor of LCNFs/Fe3O4–2//LCNFs/Fe3O4–2 also showed a remarkable power density of 7755.29 W/kg, outstanding energy density of 36.62 Wh/kg and high cycle stability (96.89 % after 5000 cycles). In short, the construction of this multifunctional lignin-based composites has potential applications in electromagnetic wave (EMW) absorbers and supercapacitor electrodes.

Electromagnetic wave absorbing ceramics composites made of polymer-derived SiC with BN@CNTs pyrolyzed higher than 1200 °C

Polymer-derived ceramics (PDCs) pyrolyzed at high temperatures are promising electromagnetic wave (EMW) absorption materials for aerodynamically heated parts of aircraft under harsh environments. Nevertheless, high-temperature pyrolysis results in a significant increase of electrical and dielectric properties of the ceramics, causing extensive reflection of EMW. To address this challenge, boron nitride-coated carbon nanotubes (BN@CNTs) were fabricated and introduced into polymer-derived SiC (PDC-SiC) by pyrolyzing its precursor higher than 1200 °C to form SiC-BN@CNT ceramic composites. The fabricated composites with 3 wt.% BN@CNTs pyrolyzed at 1200 °C have an effective absorption bandwidth (EAB) of 4.2 GHz (8.2–12.4 GHz) at a thickness of 3.4 mm and the minimum reflection loss (RLmin) of –57.20 dB. The ultra-broad EAB of 12.62 GHz (5.38–18 GHz) is obtained by simulation through periodic structure designing. The RL of the metamaterials was also measured using an arch testing method at a frequency range of 2–18 GHz and an EAB of 11.52 GHz (6.48–18 GHz) is obtained. The excellent absorption is attributed to the BN layer that limits the electrical conduction of the ceramic composites while retaining the high loss of CNTs. The introduction of BN@CNTs causes the refinement of SiC grains, which provides plenty of interfaces and enhances the interface polarization loss. This work successfully solves the problem that PDCs pyrolyzed at elevated temperatures cannot be used as EMW absorption materials by applying BN coating on CNTs served as absorbers for PDC-SiC. The results of this work greatly broaden the application scope of the PDC systems for EMW absorption.

Hollow Co0.85Se@MoSe2 with Core–Sheath Structures Derived from Co Microchains for High Efficiency Electromagnetic Wave Absorption

Hollow and hierarchical structures are the desirable features for high-performance electromagnetic wave absorbing (EWA) materials. In this study, Co microchains were used as a matrix and a layer of MoSe2 nanosheets and nanospheres was loaded onto their surface through a one-step hydrothermal reaction. During this process, Co cations migrated from the inside to the outside of the nanowire and combined with Se anions to form hollow Co0.85Se microchains and the MoSe2 on the surface contributed to a hierarchical structure. The prepared Co0.85Se@MoSe2 composites showed dielectric and magnetic losses simultaneously, achieving a minimum reflection loss (RLmin) of −42.6 dB and an effective absorbing bandwidth (EAB) of 10 GHz (6.8–10.6 and 11.8–18 GHz) at the thickness of 2.3 mm. Co0.85Se@MoSe2 microchains were successfully synthesized for the first time using a cost-effective and simple solvothermal reaction. This work sheds light on the large-scale synthesis of Co-based microchains as well as a promising EWA material with a specific structure and multiple loss modes.

Multi-mechanism response of molten salt-modified MXene with NiCo2O4 nanosheets for enhanced electromagnetic wave absorption performance

To obtain even superior electromagnetic wave (EMW) absorption materials, research is currently focused on composite absorbers. The aim of this work is to prepare composite absorbers with multiple absorption mechanisms using 2D porous Ti3C2Tx MXene as a substrate. Here, porous Ti3C2Tx MXene nanosheets with a large layer spacing were formed through high-temperature molten salt treatment of layered Ti3C2Tx MXene nanosheets. Then, NiCo2O4 nanosheets were anchored onto the porous Ti3C2Tx MXene nanosheets through heat treatment, forming a heterogeneous structure of porous Ti3C2Tx MXene/NiCo2O4 (P-MXene/NiCo2O4). The heterogeneous interface between Ti3C2Tx MXene and NiCo2O4 nanosheets forms strong interfacial polarization, while NiCo2O4 connects the MXene layer to layer forming a conductive network structure. Furthermore, NiCo2O4 nanosheets suppress the self-stacking of porous Ti3C2Tx MXene nanosheets and improve impedance matching. As a result, P-MXene/NiCo2O4 offers excellent EMW absorption performance with a reflection loss (RL) value of − 64.7 dB at a matching thickness of 4.465 mm. This study provides a new idea for pretreating Ti3C2Tx MXene and constructing efficient composite absorbing materials for electromagnetic waves.

Kapok fibers-derived carbon microtubes as efficient electromagnetic wave absorption materials

The superior electromagnetic wave absorption materials have the characteristics of thin matching thickness, low density, wide absorption bandwidth and strong absorption intensity, which can effectively deal with electromagnetic pollution. With the further research, biomass-derived carbon has received great focus due to abundant biological reserves and unique natural structure. Herein, we put forward an excellent electromagnetic wave absorption material, carbon microtubes (CMTs) with a one-dimensional hollow tubular structure, which derived from kapok fibers (KFs) via a facile annealing method. The result shows that the effective absorption bandwidth (EAB) of CMTs is 6.78 GHz under 900 °C annealing conditions. Especially, the filling ratio is just 3 wt% and the matching thickness is 2.06 mm. The superior electromagnetic wave absorption properties of CMTs can be related to its microstructural characteristics. This one-dimensional tubular structure has a large specific surface area increasing the interaction area between the material and electromagnetic waves, while the hollow tube cavity can make the incident electromagnetic waves for multi-ply scattering and reflection strengthening the dissipation capability of the material. This work offers a convenient way to produce effective electromagnetic wave absorption materials with low cost and eco-friendly environment.

Electromagnetic wave absorption mechanism for nanocomposites of holmium orthoferrite decorated poly(3,4-ethylenedioxythiophene -5-cyanoindole)

New microwave absorbents with low thickness, minimum reflection loss and effective absorption bandwidth microwave absorption capabilities are urgently needed, but their realization remains still challenging. For this study, we used an innovative nanocomposite architecture comprised of polygonal HoFeO3 powder encapsulated with Poly(EDOT-co-CNIn) to create an electromagnetic wave absorption material optimized for the X-band frequency. Structural, morphological, magnetic, and microwave absorption characteristics of synthesized nanocomposite materials were evaluated utilizing XRD, FTIR, FESEM, VSM, and VNA techniques. With 35 wt.% filler loading, HoFeO3@Poly(EDOT-co-CNIn) composite absorber achieves a minimum reflection loss (RLmini) of -40 dB having 1.6 mm thickness, as measured by the waveguide method. Compared to other absorber samples optimal sample featured improved impedance matching abilities, better attenuation coefficient and a high absorption capacity. The optimal sample is also tested using the free-space measurement technique having dimensions of 200 mm × 200 mm and thus the findings show that they accord well with those of the waveguide approach. This work presents a design strategy for an effective microwave absorbent with practical measuring strategies for both waveguide and free-space setups.

Anion Exchange of Metal Particles on Carbon-Based Skeletons for Promoting Dielectric Equilibrium and High-Efficiency Electromagnetic Wave Absorption.

The combination of carbon materials and magnetic elements is considered as an effective strategy to obtain high-performance electromagnetic wave (EMW) absorption materials. However, using nanoscale regulation to the optimization of composite material dielectric properties and enhanced magnetic loss properties is facing significant challenges. Here, the dielectric constant and magnetic loss capability of the carbon skeleton loaded with Cr compound particles are further tuned to enhance the EMW absorption performance. After 700 °C thermal resuscitation of the Cr3-polyvinyl pyrrolidone composite material, the chromium compound is represented as a needle-shaped structure of nanoparticles, which is fixed on the carbon skeleton derived from the polymer. The size-optimized CrN@PC composites are obtained after the substitution of more electronegative nitrogen elements using an anion-exchange strategy. The minimum reflection loss value of the composite is -105.9dB at a CrN particle size of 5nm, and the effective absorption bandwidth is 7.68GHz (complete Ku-band coverage) at 3.0mm. This work overcomes the limitations of impedance matching imbalance and magnetic loss deficiency in carbon-based materials through size tuning, and opens a new way to obtain carbon-based composites with ultra-high attenuation capability.

Phragmites-derived magnetic carbon fiber with hollow assembly architecture toward full-covered effective bandwidth at Ku band

Lightweight and efficient electromagnetic wave absorption (EMA) materials are in high demand, and magnetic carbon fiber composites show potential. However, impedance matching issues make achieving full coverage of the Ku band challenging, hindering improvements in effective absorption bandwidth. This study proposes innovative compositional and structural designs coupling magnetic carbon fibers to balance electromagnetic attenuation and impedance matching. We assemble 1D phragmites-derived hollow carbon fibers (PCF) with 3D CoFe2O4 (CFO) hollow nanoparticles to create a composite with two different dimensions and mechanisms of loss. CFO hollow nanoparticles uniformly distributed on the PCF conductively lose energy and enable multiple reflections. Furthermore, by designing the thermal decomposition temperature and magnetic components, high-frequency electromagnetic parameters can be controllably adjusted. Notably, PCF7-CFO exhibits excellent reflection loss of −57.8 dB at 14.8 GHz with a filling ratio of 20 wt% and matching thickness of 2.0 mm, with an effective absorption bandwidth reaching 5.9 GHz, almost covering the entire Ku band. The hollow-assembly structure balances impedance matching and high-frequency attenuation, achieving full-Ku-band coverage for developing efficient electromagnetic wave absorbers with biomass-derived carbon materials.

Lightweight polyurethane composite foam for electromagnetic interference shielding with high absorption characteristic

Due to the rapid growth of electronic equipment technology, efficient electromagnetic shielding materials are needed for equipment and human protection. Among them, foam shielding materials with absorption as the primary mechanism have higher application value than highly reflective materials. Highly absorbing shielding materials can reduce the secondary pollution caused by electromagnetic wave reflection. In this study, we added Fe3O4@Polyvinyl alcohol (Fe3O4@PVA) and graphene oxide@silver (GO@Ag) into the polyurethane (PU) matrix and constructed Fe3O4@PVA and GO@Ag/PU composite foam by foaming. Fe3O4@PVA and GO@Ag form an excellent network structure in the PU foam skeleton, significantly improving its electromagnetic shielding effectiveness (EMI SE) and mechanical properties. The shielding effectiveness reached 30.9 dB with a specific EMI SE (SSE) of 274.9 dB × cm3 × g−1 at a Fe3O4@PVA filling of 7 wt%, where the electromagnetic wave absorption accounted for more than 80 % of the total EMI SE, proving absorption as the primary shielding mechanism. The results show that Fe3O4, as a ferromagnet, has both the dielectric loss of ferroelectric materials and the hysteresis loss of ferromagnetic materials in electromagnetic shielding, effectively improving the wave absorption performance of composite shielding materials. Therefore, this work provides a promising idea for efficient and lightweight wave-absorbing shielding materials in aerospace, portable electronic devices and lightweight wearable devices.

Achieving wideband electromagnetic wave absorbing performance for PMMA-based composites foam by designing the alternating directional (AD) microporous structure

Good impedance matching and attenuation ability of electromagnetic wave absorbing (EMA) materials are required to broaden the effective absorbing bandwidth (EAB) and reduce minimum reflection loss (RLmin), achieving high EMA performance. Here we report a polymethylmethacrylate (PMMA)-based composites foam with alternating and directional (AD) microporous structure that possessing broadened EAB value of 3.53 GHz (8.49–12.02 GHz) and lowered RLmin value of −19.35 dB, was manufactured via the one-step physical constraint foaming technology. Structural studies reveal that the AD microporous structure can induce the carbon nanotubes (CNTs) oriented distribution to improve effective concentration of CNTs, achieving excellent impedance matching. Meanwhile, a large number of parallel-plate capacitors at the multilayer layer interfaces were generated to promote interfacial polarization, including enhancement of multiple reflection and scattering of electromagnetic wave at the layer interfaces. Thereby, the composites foams exhibited high attenuation ability. This study lays the foundation for rational design and synthesis of EMA materials for wideband EMA performance.

Concocting of FeO nanoparticles by coalescence of metal oxides for supercapacitor applications

Iron oxide (FeO) nanoparticles have gained considerable interest from researchers over the past few decades and have a massive effect on wave absorption materials, magnetic fluid, adsorbent, and a variety of industrial applications. In this study, ferric nitrate, sodium hydroxide, and ammonium hydroxide coalesced to form FeO nanoparticles using the chemical co-precipitation approach. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), UV-VIS analysis, Photoluminesence (PL) spectrum analysis, and electrochemical measurements were used to characterize FeO nanoparticles. As per XRD, the sample’s crystallite size was 22.63[Formula: see text]nm and 22.64[Formula: see text]nm after it was annealed at 300∘C and 400∘C, respectively. Utilizing XRD, the diffraction patterns were seen. The particles appear to have a fine surface and smooth shape, as seen by SEM photographs. For the detection of FeO nanoparticles, optical and electrochemical examinations were carried out.

Electrostatic self-assembly hollow-VOOH/MXene composite for microwave absorption

In this study, hollow-structured hydroxy vanadium oxide (VOOH) was constructed and VOOH@MXene composite material was prepared through electrostatic self-assembly. The composites can effectively attenuate and absorb electromagnetic waves. Among them, the excellent conductivity of MXene can make up for the low conductivity of hydroxy vanadium oxide, and the hollow structure of hydroxy vanadium oxide can effectively prevent the stacking of MXene sheet layers and improve the poor impedance matching problem. The composite VOM_10 has good microwave absorption performance with a minimum reflection loss of −34.9 dB and a maximum effective absorption bandwidth of 4.08 GHz. The preparation of VOOH@MXene composites using an electrostatic self-assembly strategy and construction of a hollow structure strategy provides a new idea for the study of new lightweight and high performance wave absorption materials.