Metal–Organic Framework-Derived Core–Shell Nanospheres Anchored on Fe-Filled Carbon Nanotube Sponge for Strong Wideband Microwave Absorption

Abstract

Metal−organic frameworks (MOFs) are booming as a promising precursor for constructing lightweight, highefficiency microwave absorbing (MA) material. However, it is still a challenge to rationally design three-dimensional (3D), porous MOF-derived MA materials with a stable structure and strong and wideband MA performance. Herein, a 3D hybrid nanostructure (CNT/FeCoNi@C) comprising MOF-derived magnetic nanospheres and Fe-filled carbon nanotube (CNT) sponge has been controllably fabricated to enhance the absorption ability and broaden the effective absorption bandwidth (EAB). The magnetic nanospheres are uniformly anchored on the CNT skeleton, forming hybrid network structures, which enhance interface polarization, electron transportation, and impedance matching. The minimum reflection loss (RL) and EAB of the asprepared CNT/FeCoNi@C sponges reach −51.7 dB and 6.0 GHz, respectively, outperforming most reported MOF-based wave absorbers. This work provides not only a novel design of MOF-derived 3D nanostructures but also an effective guide for the optimization of electromagnetic properties and absorbing performance in MA material.

Fe-Ti oxides/carbon composites derived from temperature-dependent solid-state reaction between MOFs core and TiO2 shell for broadband microwave absorption

“…Figure 8i summarizes RL peak values of similar MAMs. Minimum RL value of -42.38 dB can be reached at thickness of 2.4 mm for S-800, which can meet most practical situations [24,25,29,[38][39][40][41][42]. Figure 8j lists EAB of reported MAMs.…”

Morphology-Controlled Fabrication Strategy of Hollow Mesoporous Carbon Spheres@f-Fe2O3 for Microwave Absorption and Infrared Stealth

“…The curves of ε″ versus ε′ are plotted in Figure g–j. According to the Debye theory, one Debye relaxation process corresponds to one semicircle (Cole–Cole semicircle) , where ε s and ε ∞ are the static permittivity and relative permittivity at the high-frequency limit, respectively. It could be observed that multiple Debye relaxation processes existed in HMCS@f-Fe 2 O 3 - x under an external alternating electric field.…”

“…j. According to the Debye theory, one Debye relaxation process corresponds to one semicircle (Cole−Cole semicircle)6,37 …”

Engineering of the Core–Shell Boron Nitride@Nitrogen-Doped Carbon Heterogeneous Interface for Efficient Heat Dissipation and Electromagnetic Wave Absorption

“…Currently, the multi-interface engineering of dielectric materials can promote interfacial polarization. Various core–shell-structured nanocomposites have been designed to enhance EWA properties. − Inspired by this idea, rational construction of a BN@carbon core–shell structure may facilitate the attenuation of EW and heat dissipation, while the related research work has not been reported. The core–shell structure ensures a strong contact between the BN and carbon shell.…”