In this paper, the structure evolution of cerium cobaltohexanoate (Ce[Co(CN)₆], Ce-Co Prussian blue analog (PBA)) has been realized by solvent catalysis at room temperature. The hexagonal bipyramidal microcrystals of Ce-Co PBA can be gradually transformed into dendrites by different proportions of ethanol (EtOH) and water. At the same time, the porous dendrites CeO₂/Co@carbon nanotub (CNT) with oxygen-rich vacancies (OVs) can be obtained by annealing Ce-Co PBA at 700 °C. The microstructure study shows that carbon nanotubes will be catalyzed after annealing at high temperature, and the cobalt metal particles encapsulated in carbon nanotubes will be anchored in the matrix, regulating the impedance matching and multi-polarization suppression of the material, and its unique structure, vacancies, and strong interface effect make the material exhibit excellent electromagnetic wave (EMW) absorption performance. When the matching thickness is 2.5 mm, the minimum reflection loss (RL_min) of the composite is −51.68 dB, and the effective absorption bandwidth (RL < −10 dB) is 7.76 GHz. These results show that the prepared CeO₂/Co@CNT composite has excellent EMW absorption properties. It is expected to be a candidate material for EMW absorption.

Confronted with severe electromagnetic wave pollution, the development of high-performance electromagnetic wave shielding or absorbing materials is an effective way to deal with it. Notably, double transition metal alloys and transition metal dichalcogenides have attracted extensive attention in electromagnetic wave absorption, but few reports have studied the effects of these two materials on electromagnetic wave absorption at the same time. In this work, cobalt-based alloy with magnetic loss mechanism was selected for composition optimization. The ternary metal-organic framework was prepared by the one-step method, and then CoCu/C was prepared by high temperature annealing. Finally, in the hydrothermal process, ultra-thin tungsten selenide nanosheets were coated on the surface of magnetic component, and the final polyhedral WSe₂/CoCu/C composites with multiple heterogeneous interfaces were obtained. The synergistic effect of dielectric and magnetic components optimizes impedance matching and allows more electromagnetic waves to enter the absorber. Subsequently, through the conduction loss of high conductivity graphitized carbon, interfacial polarization, and dipole polarization of heterogeneous interfaces between the components, the magnetic loss provided by CoCu alloy can work together to maximize the attenuation ability of electromagnetic waves. Exactly, the minimum reflection loss (RL_min) value of the composite reaches −53.43 dB when the matched thickness is 2.1 mm, while the maximum effective absorption bandwidth (EAB_max) reaches 6.0 GHz at a thin thickness of 1.8 mm. This work provides some support and reference for the design of novel electromagnetic wave absorbing materials via the dielectric/magnetic loss synergistic mechanism.

To achieve excellent electromagnetic wave (EMW) absorption properties, the microstructure design of the absorber is critical. In this work, six kinds of N-Ni/C nanostructures with different morphologies were prepared by one-step hydrothermal method and high temperature carbonization by adjusting the types of nickel salts and reaction solvents. The EMW absorption performance of six different morphologies of N-Ni/C nanostructures was compared and analyzed. Among them, it is found that the nanoflower-like N-Ni/C composite has excellent dielectric loss and magnetic loss synergistic effect due to its polycrystalline structure, and can obtain excellent EMW absorption performance. The minimum reflection loss value at a thickness of 1.9 mm is −59.56 dB at 16.88 GHz, and the effective absorption bandwidth value reaches 6.0 GHz at a thickness of 2.2 mm. Our research shows that different morphologies and multiple lattice structures of nanostructures with the same composition have a significant influence on EMW absorption performance, which provides new research ideas for developing high-performance EMW absorbing materials.

Two-dimensional metal carbide or nitride materials (MXenes) are widely used in electromagnetic wave absorption because of their unique structure. Herein, a novel composite preparation strategy has been proposed to design dendritic nanofibers based on the electrostatic spinning methods. The multifunctional MXene nanosheets are used as the dendritic matrix, and magnetic nanoparticles are embedded in the nanosheets as magnetic loss units. Multidimensional nanocomposites have interlaced carbon fiber networks, large-scale magnetically coupled networks, and a lot of multi-heterojunction interface structures, which endow the composites with extraordinary conduction loss, magnetic loss, and polarization loss capabilities, respectively. The impedance matching and loss mechanisms of the composites are improved by optimizing the synergistic relationship between the components and building a suitable structure. The optimum reflection loss (RL) of −54.1 dB is achieved at 2.7 mm and a wide effective absorption bandwidth (EAB, RL below −10 dB) of 7.76 GHz is obtained at a small thickness of 2.1 mm for the nanocomposites. The distinctive microstructures of the nanofibrous membranes give rise to their flexibility, waterproof, and electromagnetic wave absorption performance and endow the nanofibrous membranes potential to be utilized as lightweight, efficient electromagnetic wave protective fabric in harsh environment.

The weak dielectric properties and the lack of magnetic loss of manganese-based absorbers are obstructed as the new generation of electromagnetic wave absorption (EMA) materials applying in microelectronic devices. Herein, the sulfuration and subsequent compounding strategies have been employed to enhance the EMA performance of multi-shell nanosphere-shaped Mn₂O₃ materials. With the narrow bandgap, the as-obtained MnS possesses reinforced electrical conductivity, which is conducive to conductivity loss. More importantly, the presence of potential difference between different phases will form space charge region at the heterogeneous interface, thus favoring interfacial polarization. Additionally, the improvement of magnetic loss is attributed to the presence of Co₃O₄ nanoparticles. Consequently, the composites present enhanced EMA performance than original Mn₂O₃. Specifically, the minimum reflection loss of as-prepared composites is −51.4 dB at the thickness of 1.8 mm and the broad effective absorption bandwidth reaches 6.2 GHz at 1.9 mm. The low matching thickness and high absorption efficiency in this work can provide a convincing reference when designing distinguished manganese-based absorbers.