Tunable high-performance microwave absorption of cobalt nanoparticles wrapped in N-self-doped carbon nanofibers at ultralow filler loadings

Low-Cost and Eco-Friendly Synthesis of CoFe2 Nanoparticles Encapsulated into Porous Carbon Nanofibers as a Lightweight and High-Performance Microwave Absorber

“…It shows that the C 1s spectrum (Figure S3b) can be decomposed into three peaks located at 284.8, 285.8, and 288.2 eV, corresponding to the C−C/C�C, C−N, and C�O groups, respectively. 8 Figure S3c shows that the Fe 2p spectrum can be attributed to the metallic states of Fe 0 (711.2 eV for 2p 3/2 and 719.5 for 2p 1/2 ) and Fe 2+ (715.3 eV for 2p 3/2 , 724.0 for 2p 1/2 , and 730.4 for the satellite peak of Fe 2p 1/2 ). 30 As presented in Figure S3d, the two peaks at 780.9 and 796.0 eV are indexed to metallic Co 0 , and the other two at 785.8 and 802.6 eV are assigned to the Co 2+ oxidation state.…”

“…To obtain detailed chemical information for each element, peak fitting was applied. It shows that the C 1s spectrum (Figure S3b) can be decomposed into three peaks located at 284.8, 285.8, and 288.2 eV, corresponding to the C–C/CC, C–N, and CO groups, respectively Figure S3c shows that the Fe 2p spectrum can be attributed to the metallic states of Fe 0 (711.2 eV for 2p 3/2 and 719.5 for 2p 1/2 ) and Fe 2+ (715.3 eV for 2p 3/2 , 724.0 for 2p 1/2 , and 730.4 for the satellite peak of Fe 2p 1/2 ) .…”

“…The magnetic CoFe 2 NPs are wrapped in graphite and isolated from each other, which weakens the interactions between CoFe 2 NPs and decreases the magnetic loss by a certain degree. Generally, the magnetic loss is primarily attributed to the eddy current effect, natural and exchange resonance in the GHz band . It is known that the equation C 0 = μ″(μ′) −2 f –1 = 2πμ 0 σ d 2 /3 is utilized to verify the eddy current effect, where μ 0 and d , respectively, are permeability in vacuum and absorber thickness.…”

“…In particular, nanostructured ferromagnetic metals exhibit excellent electromagnetic wave absorption performance resulting from large saturation magnetization (M s ), high Snoek's limit, and enhanced anisotropy field (H A ). 8 Among them, ferromagnetic alloys, such as FeCo nanoparticles (NPs), serve as an important category and have been widely studied. Lv et al synthesized hexagonal cone-like Fe 50 Co 50 NPs which provide a reflection loss (RL) value of −22 dB and an EAB of 7.1 GHz.…”

Biologically Inspired Nanoporous PAN/PMMA/β-CD Carbon Fibers for Efficient Microwave Absorption

“…Impedance matching and attenuation characteristics determine the performance of MAMs significantly, both of which are influenced by composition, microstructure, thickness, and filling ratio. , Excellent impedance matching can meet the requirements for microwaves to enter the interior of the material, which is a prerequisite for the material to possess an excellent absorption performance. However, a carbon material with a single component is weak in impedance matching.…”