Hierarchical and Orderly Surface Conductive Networks in Yolk–Shell Fe₃O₄@C@Co/N‐Doped C Microspheres for Enhanced Microwave Absorption

Abstract

Constructing the adjustable surface conductive networks is an innovation that can achieve a balance between enhanced attenuation and impedance mismatch according to the microwave absorption mechanism. However, the traditional design strategies remain significant challenges in terms of rational selection and controlled growth of conductive components. Herein, a hierarchical construction strategy and quantitative construction technique are employed to introduce conductive metal–organic frameworks (MOFs) derivatives in the classic yolk–shell structure composed of electromagnetic components and the cavity for remarkable optimized performance. Specifically, the surface conductive networks obtained by carbonized ZIF‐67 quantitative construction, together with the Fe3O4 magnetic core and dielectric carbon layer linked by the cavity, achieve the cooperative enhancement of impedance matching optimization and synergistic attenuation in the Fe3O4@C@Co/N‐Doped C (FCCNC) absorber. This interesting design is further verified by experimental results and simulation calculations. The products FCCNC‐2 yield a distinguished minimum reflection loss of −66.39 dB and an exceptional effective absorption bandwidth of 6.49 GHz, indicating that moderate conduction excited via hierarchical and quantitative design can maximize the absorption capability. Furthermore, the proposed versatile methodology of surface assembly paves a new avenue to maximize beneficial conduction effect and manipulate microwave attenuation in MOFs derivatives.

MoS2-Based Nanocomposites for Microwave Absorption: A Review

“…The common dielectric losses are relaxation polarization loss and conduction loss in microwave absorption. − Under the action of an electric field, a leakage conduction current will be generated inside any dielectric material but dissipated in the form of heat, which results in conduction loss. − Furthermore, the relaxation polarization loss is caused by the current inside the material due to the relaxation polarization of the dielectric. − Among the dielectric polarization theory, the Debye relaxation theory should be the most widely used and most mature. , According to the Debye relaxation theory, the real and imaginary part of the permittivity of materials is not independent and they have such a relationship: true( ε ′ − ε normals + ε ∞ 2 true) 2 + false( ε ″ false) 2 = true( ε normals − ε ∞ 2 true) 2 where ε′ refers to the real part of the permittivity, ε″ refers to the imaginary part of the permittivity, ε s is the static permittivity, and ε ∞ is the optical frequency permittivity. It is generally believed that the relationship between the real and imaginary values of the permittivity is a semicircle in an ideal case .…”

Construction of Hierarchical Yolk–Shell Co/N-Dope C@void@C@MoS2 Composites with Multiple Heterogeneous Interfaces toward Broadband Electromagnetic Wave Absorption

“…Owing to the unique design, these microspheres presented outstanding EMW absorption properties, with an excellent reflection loss (RL) of −66.39 dB and an effective absorption bandwidth (EAB) of 6.49 GHz. 25 Liang et al synthesized a series of cubelike yolk−shell structural nanocomposites derived from Prussian blue analogues. Among them, FeCo@void@C exhibited the most favorable EMW absorption characteristics.…”

“…In their report, He et al described the synthesis of Fe 3 O 4 @C@Co/N-doped C yolk–shell microspheres. Owing to the unique design, these microspheres presented outstanding EMW absorption properties, with an excellent reflection loss (RL) of −66.39 dB and an effective absorption bandwidth (EAB) of 6.49 GHz . Liang et al synthesized a series of cubelike yolk–shell structural nanocomposites derived from Prussian blue analogues.…”

Multilevel Heterogeneous Interfaces Enhanced Polarization Loss of 3D-Printed Graphene/NiCoO2/Selenides Aerogels for Boosting Electromagnetic Energy Dissipation

“…4,5 According to the principle of component coordination and structural design, constructing heterogeneous structures has been considered as an effective strategy to improve the attenuation ability of EM wave absorbing materials. 6 Up to now, two main kinds of heterogeneous structures have been presented in the literature. 7 One is the heterogeneous interfaces formed when different materials are compounded.…”