Synthesis of Nonspherical Hollow Architecture with Magnetic Fe Core and Ni Decorated Tadpole‐Like Shell as Ultrabroad Bandwidth Microwave Absorbers

Abstract

The advancement of electromagnetic (EM) protection technology promotes the urgent demand for the structural design of electromagnetic functional materials. Here, tadpole‐like Fe@SiO2@C‐Ni (FSCN) composites with magnetic core–shell and nonspherical hollow architectures through multiple hydrolysis‐polymerization reactions are reported. The Fe core and well‐distributed Ni nanoparticles greatly promote the magnetic properties of FSCN and construct a multiscale magnetic coupling network. Meanwhile, the multishell composites consisting of carbon shell with Ni decorated possess an abundance of heterogeneous interfaces, generating effective interfacial polarization and relaxation. The hollow feature and the coordination of magnetic and dielectric capacities offer an optimized impedance balance, providing a fundament for the microwaves propagating into the absorber. Owing to the attractive effects resulted from the deliberate tadpole‐like structure design, the FSCN composites ensure an effective EM energy conversion at the high‐frequency region, which obtain the strongest reflection loss value of −45.2 dB and the extremely broad effective absorption bandwidth of 13.1 GHz. This work provides an important solution for magnetic‐dielectric nanostructure design for microwave absorption and energy conversion materials.

The excellent electromagnetic wave absorbing properties of carbon fiber composites: the effect of metal content

“…8,9 For example, with the synergistic effect of dielectric and magnetic losses, Guo and his co-workers synthesized rod-like ZnO@Fe core–shell composites, which achieved a minimum RL of −48.0 dB at 1.5 mm. 10 Li et al prepared tadpole-like hollow Fe@SiO 2 @C–Ni composites, 11 which exhibited a broad effective absorption bandwidth of 13.1 GHz and a minimum RL value of −45.2 dB. Cobalt is one of the attractive candidates for EM absorption at high temperatures due to its high Curie temperature.…”

Selective assembly of magnetic nano-antenna for electromagnetic dissipation

“…36 α-Fe 2 O 3 @SiO 2 was synthesized by a sol–gel process of silica nanorods growing on cube-like α-Fe 2 O 3 particles as reported previously. 18,34 30 μL of as-obtained α-Fe 2 O 3 solution was injected into 10 mL of 0.1 g mL −1 PVP ( M w ∼ 55 000) and n -pentanol solution, followed by the sequential addition of 100 μL sodium citrate (0.2 mol L −1 ), 200 μL ammonium hydroxide solution (NH 3 ·H 2 O, 25–28 wt%) and 1 mL ethanol (≥99.7%). The assembling of silica capsules was initiated by injection of 100 μL tetraethyl orthosilicate (TEOS).…”

“…[4][5][6][7][8][9][10][11] Double-shell structures can regulate impedance matching precisely by introducing controllable heterojunction contacts and a fast electronic transmission channel to improve conductivity. [12][13][14][15][16][17][18] Previously, trilaminar electromagnetic synergistic systems usually consisted of a magnetic core with double dielectric coatings like Fe/Fe 3 O 4 @TCNFs@TiO 2 , 19 CoNi@SiO 2 @TiO 2 , 20 and Co@SiO 2 @Void@C, 21 or a dielectricmagnetic-dielectric sandwich-like structure, such as TiO 2 @-Fe 3 O 4 @ppy, 22 or akes, particles, and CNT-decorated core-shell assemblies like Fe 3 O 4 /Fe@C@MoS 2 23 and Mo 2 N@CoFe@C/ CNT. 24 The rational arrangement of each wrapping layer is signicant to import more microwaves into the EM absorber.…”

Macroscopic Electromagnetic Cooperative Network-Enhanced MXene/Ni Chains Aerogel-Based Microwave Absorber with Ultra-Low Matching Thickness

“…This network not only induces magnetic loss for enriching attenuation mechanism but also produces interfacial effects due to the existence of heterogeneous interface nearby, which will affect the crystal and electronic structure [ 11 ]. After Che’s group firstly proposed this idea in 2004 [ 12 ], numerous EMW absorbers with various component collocation and structural construction were developed and explored based on the idea of electromagnetic cooperation [ 13 , 14 ]. The electromagnetic cooperative effect of most absorbers mainly exists at the microscopic or mesoscopic scales.…”