The development of multifunctional electromagnetic wave-absorbing materials capable of operating in complex environments has become critically important in the field of electromagnetic protection. However, achieving materials that combine high absorption efficiency with exceptional thermal stability remains a significant challenge. Owing to their lightweight hollow structure, low thermal conductivity, and high thermal stability, hollow SiC/C fibers present a promising solution to the problem of high-temperature electromagnetic wave absorption. In this study, hollow SiC/C nanofibers were successfully synthesized via a combined hydrothermal and carbothermal reduction approach. The resulting hollow SiC/C nanofibers exhibit ultralight characteristics, high-temperature stability, good elasticity and fatigue resistance, and exceptional electromagnetic wave absorption performance, including an effective absorption bandwidth of 7.0 GHz at a thickness of 2.4 mm and an optimal reflection loss of −63.5 dB at a thickness of 1.4 mm. Moreover, the material demonstrates remarkable high-temperature dielectric stability, with its complex permittivity remaining virtually unchanged at 600 °C. The formulated strategy provides a feasible approach for designing SiC matrix composites with stable dielectric properties and efficient electromagnetic wave absorption.

The design and fabrication of efficient microwave absorbing materials with tunable wave attenuation capacity to address the increasing demand for electromagnetic pollution mitigators remains a challenging task. In this study, Ag₂Te and a series of Ag/Ag₂Te composites have been successfully synthesized by using a facile one-step solvothermal method through varying the molar ratio of the reactants and reaction time. To investigate the microwave absorption performance of these composites, the samples are mixed with polyvinylidene difluoride matrix under different filler ratios. The experimental results indicate that the AT3 (where the molar ratio of Ag:Te is 4:1) sample possesses optimal wave dissipation ability with a minimum reflection loss value of −55.98 dB at 15.01 GHz and a maximum effective absorption bandwidth of 4.90 GHz (13.10−18.00 GHz) at a thickness of 1.7 mm when the filler content is 10 wt.%. Moreover, the widest EAB of 6.20 GHz (10.60−16.80 GHz) is recorded in the Ag₂Te sample. Meanwhile, it is observed the solvothermal reaction time can effectually influence effective wave absorption frequency. As the reaction time increases, the position of the minimum reflection loss (RL_min) shifts to lower frequencies. The analysis of the wave absorption mechanism demonstrates that the novel crooked one-dimensional linear structure and abundant heterogeneity within the Ag/Ag₂Te composite plays an important role in achieving outstanding wave absorption performance. The specific wave absorption mechanism includes conductive loss, multiple scattering, multiple resonant coupling, interface polarization and electric dipole polarization. This work can provide an effective strategy for the design of high-performance MAMs through constituent and morphology modulation.

In order to alleviate the growing problem of electromagnetic radiation pollution, it is both urgent and challenging to develop electromagnetic wave absorbing materials with strong absorption and wide effective absorption bandwidth (EAB). The structural design of heterojunction surfaces plays an important role in the development of advanced microwave absorbing materials. Building on this concept, three-dimensional nanocomposites Alk-Ti₃C₂T_x/nitro metal phthalocyanine (TNMP) with phthalocyanine derivative NMP-MXene are designed. TNMP composites are prepared by self-assembly of surface hydroxylated treated MXene with floral spherical nitrophthalocyanine. This method effectively constructs rich heterojunction surfaces and induces dipole polarization effect by designing a large number of oxygen vacancies through coordination, which effectively enhances the material attenuation capability while balancing impedance matching characteristics. By modulating the metal centers in the NMP, the coordination mode of the heterojunction surfaces is regulated, and the polarization relaxation loss is improved to achieve excellent electromagnetic wave absorption performance (reflection loss (RL) of −62.12 dB at a thickness of 1.25 mm). And based on the bionic structure design, a unit cycle structure of double-layered butterfly wing skeleton (DLBWS) is constructed to obtain an ultra-wideband electromagnetic wave absorber with an EAB of 12.5 GHz. This research demonstrates a regulatory scheme to elucidate the dipole polarization mechanism and proposes a new method for designing functional materials in ultra-broadband electromagnetic wave absorption.

Here, we present a unique method to enhance the low-frequency absorption performance of a honeycomb absorber by integrating a metasurface. The geometrical dimensions of the proposed metasurface have been numerically optimized. The introduction of the metasurface allows exploitation of its robust resonance and superior impedance matching in low-frequency bands, thereby improving microwave absorption properties. The incorporation of the metasurface does not impact the wave transmission performance of the honeycomb core absorber at high-frequency band, thus preserving its high-frequency performance. This broadens the absorption range, leading to an expanded bandwidth. Simulation results reveal that the composite absorber (CA) exhibits strong absorption performance with an incident angle stability up to 45° for both transverse electric (TE) and transverse magnetic (TM) modes. The absorption mechanism of the CA has been investigated by using an equivalent circuit model and electromagnetic field analysis. A prototype was designed, fabricated, and tested to validate the proposed method. Both simulation and measurement results demonstrate that the prototype can achieve an average absorption rate exceeding 90% across a 1.0−18.0 GHz range. This study introduces an innovative technique for creating microwave absorbers for low-frequency wideband applications.

With the rapid development of wireless communication technology and electronic devices, the issue of electromagnetic interference (EMI) is becoming increasingly severe. Developing a new and flexible electromagnetic interference shielding material has become a challenging task. Here, a sandwich-structured EMI shielding composite film was prepared using electrospinning and vacuum filtration methods. In this process, a porous MXene was synthesized through a reaction with cobalt acetate and served as the intermediate layer in the composite film to shield electromagnetic waves. The electrospun polyimide (PI) fibers were used as the top and bottom layers of the composite film, which can protect the porous MXene from oxidation. This lightweight and flexible composite film integrates electromagnetic interference shielding and thermal insulation capabilities, showing excellent comprehensive performance. The composite film achieves an EMI shielding effectiveness of 48.8 dB in X-band (8.2–12.4 GHz), and absolute shielding effectiveness of the composite film reached a satisfying 4142.43 (dB·cm²)/g. Owing to the design of a multi-layer porous structure, the density of the composite film is 0.65 g/cm³. Furthermore, the thermal conductivity of the film is 0.042 W/(m·K) due to the clamping of electrospun PI fibers, showing excellent thermal insulation performance. Additionally, the composite film exhibits excellent high and low-temperature resistance. In summary, this work provides a feasible strategy for preparing a lightweight polymer-based EMI shielding film.

The impedance mismatch of carbon materials is a key factor limiting their widespread use in electromagnetic (EM) wave absorption. In this work, the novel CeO₂/nitrogen-doped carbon (CeO₂/N-C) nanofiber was prepared to solve the problem by electrospinning and sintering. X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) analyses demonstrated CeO₂ was successfully loaded onto the surface of partially graphitized carbon fibers. Different sintering temperatures change the graphitization degree of material, and the oxygen vacancy structure of CeO₂ and defects from N doping optimize the impedance matching of the material. When the sintering temperature reaches 950 °C, CeO₂/N-C fiber possesses the minimum reflection loss (RL_min) value of −42.59 dB at 2.5 mm with a filler loading of only 3 wt.% in polyvinylidene difluoride (PVDF). Meanwhile, the CeO₂/N-C fiber achieves a surprising wideband (8.48 GHz) at a thickness of 2.5 mm, covering the whole Ku-band as well as 63% of the X-band at the sintering temperature of 650 °C. This work provides the research basis for widely commercial applications of carbon-based nanofiber absorbers.

Arm symmetrical PbS dendrite (ASD-PbS) nanostructures can be prepared on a large scale by a solvothermal process. The ASD-PbSs exhibit a three-dimensional symmetrical structure, and each dendrite grows multiple branches on the main trunk. Such unique ASD-PbSs can be combined with polyvinylidene fluoride (PVDF) to prepare a composite material with enhanced dielectric and microwave-absorption properties. A detailed investigation of the dependence of the dielectric properties on the frequency and temperature shows that the ASD-PbS/PVDF composite has an ultrahigh dielectric constant and a low percolation threshold. The dielectric permittivity is as high as 1, 548 when the concentration of the ASD-PbS filler reaches 13.79 vol.% at 102 Hz, which is 150 times larger than that of pure PVDF, while the composite is as flexible as pure PVDF. Furthermore, the maximum reflection loss can reach -36.69 dB at 16.16 GHz with a filler content of only 2 wt.%, which indicates excellent microwave absorption. The loss mechanism is also elucidated. The present work demonstrates that the addition of metal sulfide microcrystals to polymer matrix composites provides a useful method for improving the dielectric and microwave-absorption properties.