Electromagnetic (EM) wave absorbing materials play an increasingly important role in modern society for their multi‐functional in military stealth and incoming 5G smart era. Dielectric loss EM wave absorbers and underlying loss mechanism investigation are of great significance to unveil EM wave attenuation behaviors of materials and guide novel dielectric loss materials design. However, current researches focus more on materials synthesis rather than in‐depth mechanism study. Herein, comprehensive views toward dielectric loss mechanisms including interfacial polarization, dipolar polarization, conductive loss, and defect‐induced polarization are provided. Particularly, some misunderstandings and ambiguous concepts for each mechanism are highlighted. Besides, in‐depth dielectric loss study and novel dielectric loss mechanisms are emphasized. Moreover, new dielectric loss mechanism regulation strategies instead of regular components compositing are summarized to provide inspiring thoughts toward simple and effective EM wave attenuation behavior modulation.

Dielectric Loss Mechanism in Electromagnetic Wave Absorbing Materials

With the rapid development of fifth-generation mobile communication technology and wearable electronic devices, electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted worldwide attention. Therefore, the design and development of highly efficient EMI shielding materials are of great importance. In this work, the three-dimensional graphene oxide (GO) with regular honeycomb structure (GH) is firstly constructed by sacrificial template and freeze-drying methods. Then, the amino functionalized FeNi alloy particles (f-FeNi) are loaded on the GH skeleton followed by in-situ reduction to prepare rGH@FeNi aerogel. Finally, the rGH@FeNi/epoxy EMI shielding composites with regular honeycomb structure is obtained by vacuum-assisted impregnation of epoxy resin. Benefitting from the construction of regular honeycomb structure and electromagnetic synergistic effect, the rGH@FeNi/epoxy composites with a low rGH@FeNi mass fraction of 2.1 wt% (rGH and f-FeNi are 1.2 and 0.9 wt%, respectively) exhibit a high EMI shielding effectiveness (EMI SE) of 46 dB, which is 5.8 times of that (8 dB) for rGO/FeNi/epoxy composites with the same rGO/FeNi mass fraction. At the same time, the rGH@FeNi/epoxy composites also possess excellent thermal stability (heat-resistance index and temperature at the maximum decomposition rate are 179.1 and 389.0 °C respectively) and mechanical properties (storage modulus is 8296.2 MPa). 

/pdf/high-efficiency-electromagnetic-interference-shielding-of-3a08itbi.pdf

High-Efficiency Electromagnetic Interference Shielding of rGO@FeNi/Epoxy Composites with Regular Honeycomb Structures

https://link.springer.com/content/pdf/10.1007/s40820-022-00798-5.pdf

Layered 3D structure derived from MXene/magnetic carbon nanotubes for ultra-broadband electromagnetic wave absorption

A mini-review of MXene porous films: Preparation, mechanism and application

High-performance electromagnetic wave absorption and electromagnetic interference (EMI) shielding materials with multifunctional characters have attracted extensive scientific and technological interest, but they remain a huge challenge. Here, we reported an electrostatic assembly approach for fabricating 2D/1D/0D construction of Ti3C2Tx/carbon nanotubes/Co nanoparticles (Ti3C2Tx/CNTs/Co) nanocomposites with an excellent electromagnetic wave absorption, EMI shielding efficiency, flexibility, hydrophobicity, and photothermal conversion performance. As expected, a strong reflection loss of -85.8 dB and an ultrathin thickness of 1.4 mm were achieved. Meanwhile, the high EMI shielding efficiency reached 110.1 dB. The excellent electromagnetic wave absorption and shielding performances were originated from the charge carriers, electric/magnetic dipole polarization, interfacial polarization, natural resonance, and multiple internal reflections. Moreover, a thin layer of polydimethylsiloxane rendered the hydrophilic hierarchical Ti3C2Tx/CNTs/Co hydrophobic, which can prevent the degradation/oxidation of the MXene in high humidity condition. Interestingly, the Ti3C2Tx/CNTs/Co film exhibited a remarkable photothermal conversion performance with high thermal cycle stability and tenability. Thus, the multifunctional Ti3C2Tx/CNTs/Co nanocomposites possessing a unique blend of outstanding electromagnetic wave absorption and EMI shielding, light-driven heating performance, and flexible water-resistant features were highly promising for the next-generation intelligent electromagnetic attenuation system.

/pdf/flexible-and-waterproof-2d-1d-0d-construction-of-mxene-based-3v0l9266uu.pdf

Flexible and Waterproof 2D/1D/0D Construction of MXene-Based Nanocomposites for Electromagnetic Wave Absorption, EMI Shielding, and Photothermal Conversion

High-performance electromagnetic wave absorbing materials have aroused widespread interest, but their synthesis is still a tremendous challenge. Here, we demonstrated the multifunctional electromagnetic absorbing characteristics of magnetic cobalt nanoparticles suspended in carbon nanotubes/expanded graphite (Co/CNTs/EG) porous composites. The well-designed multi-component and novel nano-micro porous structure endowed Co/CNTs/EG porous composites with an enhanced electromagnetic wave absorption performance. As expected, a high reflection loss of −67.2 dB, an ultrathin thickness of 1.4 mm, a broad effect absorption bandwidth of 5.1 GHz, and an ultra-low filler loading of 3 wt% were achieved. The underlying microwave absorption mechanism was synergistic effects between conduction loss caused by electron transmission in the 3D conductive network, dielectric loss attributed to dipole and interface polarization in the porous structure, magnetic loss originating from the magnetic resonance of Co nanoparticles, and multiple reflections in the porous framework. In addition, the Co/CNTs/EG porous composites exhibited favorable waterproof, flame retardant, thermal insulation, and infrared shielding functions. Therefore, we report a flexible development strategy of novel porous composites with multifunctional and efficient electromagnetic wave absorption performances.

Enhanced electromagnetic wave absorption of magnetic Co nanoparticles/CNTs/EG porous composites with waterproof, flame-retardant and thermal management functions

Etching engineering and electrostatic self-assembly of N-doped MXene/hollow Co-ZIF hybrids for high-performance microwave absorbers

Mixed-dimensional hierarchical configuration of 2D Ni2P nanosheets anchored on 1D silk-derived carbon fiber for extraordinary electromagnetic wave absorption

Yuyang Shi

Papers

Flexible and Waterproof 2D/1D/0D Construction of MXene-Based Nanocomposites for Electromagnetic Wave Absorption, EMI Shielding, and Photothermal Conversion

Enhanced electromagnetic wave absorption of magnetic Co nanoparticles/CNTs/EG porous composites with waterproof, flame-retardant and thermal management functions

Etching engineering and electrostatic self-assembly of N-doped MXene/hollow Co-ZIF hybrids for high-performance microwave absorbers

Mixed-dimensional hierarchical configuration of 2D Ni2P nanosheets anchored on 1D silk-derived carbon fiber for extraordinary electromagnetic wave absorption

Efficient microwave absorption of MOFs derived laminated porous Ni@C nanocomposites with waterproof and infrared shielding versatility