Enhanced Microwave Absorption Performance of Coated Carbon Nanotubes by Optimizing the Fe₃O₄ Nanocoating Structure

Abstract

It is well accepted that the microwave absorption performance (MAP) of carbon nanotubes (CNTs) can be enhanced via coating magnetic nanoparticles on their surfaces. However, it is still unclear if the magnetic coating structure has a significant influence on the microwave absorption behavior. In this work, nano-FeO compact-coated CNTs (FCCs) and FeO loose-coated CNTs (FLCs) are prepared using a simple solvothermal method. The MAP of the FeO-coated CNTs is shown to be adjustable via controlling the FeO nanocoating structure. The results reveal that the overall MAP of coated CNTs strongly depends on the magnetic coating structure. In addition, the FCCs show a much better MAP than the FLCs. It is shown that the microwave absorption difference between the FLCs and FCCs is due to the disparate complementarities between the dielectric loss and the magnetic loss, which are related to the coverage density of FeO nanoparticles on the surfaces of CNTs. For FCCs, the mass ratio of CNTs to Fe is then optimized to maximize the effective complementarities between the dielectric loss and the magnetic loss. Finally, a comparison is made with the literature on FeO-carbon-based composites. The FCCs at the optimized CNT to Fe ratio in the present work show the most effective specific RL (28.7 dB·mm) and the widest effective bandwidth (RL < -10 dB) (8.3 GHz). The excellent MAP of the as-prepared FCC sample is demonstrated to result from the consequent dielectric relaxation process and the improved magnetic loss. Consequently, the structure-property relationship revealed is significant for the design and preparation of CNT-based materials with effective microwave absorption.

Boosted Interfacial Polarization from Multishell TiO2@Fe3O4@PPy Heterojunction for Enhanced Microwave Absorption

“…In addition, the moderate attenuation constant and impendence matching also make the TF@PPy composite a prospect candidate for the excellent MA material (Figure S4, Supporting Information). Compared with other relative absorbers ( Table ), the hierarchical TF@PPy composite demonstrates considerable merits such as enhanced absorption properties, adjustable absorption frequency, and thin coating thickness (Figure g–i), which cater to the requirements of wider applicability in the microwave absorption . As mentioned above, the involved microwave absorption mechanisms can be divided into the following aspects ( Scheme ): a)Polarization loss: By comparing with TiO 2 @Fe 3 O 4 , the complex permittivity of TF@PPy increases significantly, demonstrating the excellent dielectric properties (Figure a,b).…”

Template‐Free Formation of Uniform Fe3O4 Hollow Nanoflowers Supported on Reduced Graphene Oxide and Their Excellent Microwave Absorption Performances

“…Generally, the incident EM microwaves can be dissipated and absorbed as a result of being repeatedly scattered and reflected between the interfaces. Thus, the plentiful interfaces between Fe 3 O 4 and rGO can improve the microwave absorption properties through the interface loss …”

Significant promotion of porous architecture and magnetic Fe3O4 NPs inside honeycomb-like carbonaceous composites for enhanced microwave absorption

“…Besides, the effective absorption (below À10 dB) bandwidth reached 5.8 GHz (from 11.9 to 17.7 GHz) at an absorber thickness of 2 mm and could be tuned between 8.0 and 17.7 GHz by tuning the thickness between 1.0 and 2.5 mm. All the results suggest that the Fe 3 O 4 /WPC-600 composites exhibited improved microwave absorption performance over a wide frequency range, which completely covered the X band (8)(9)(10)(11)(12) GHz) and the whole Ku band (12)(13)(14)(15)(16)(17)(18), which implies that they may have useful applications in military radar systems, satellite communications and weather radar owing to their As shown in our previous discussion, poor impedance matching is not benecial for microwave absorption performance. Therefore, it was proved that Fe 3 O 4 /WPC-600 exhibited the best microwave absorption performance owing to the synergistic effect between lightweight conductive porous carbon with dielectric loss and Fe 3 O 4 nanoparticles with magnetic loss.…”

“…Hence, traditional efforts normally classied microwave-absorbing materials into two categories, namely, magnetic loss materials such as Fe, Co, Ni and alloys [9][10][11][12] and dielectric loss materials such as CuS, SiC, MnO 2 and conducting polymers. [13][14][15][16] Unfortunately, their high density greatly limits their potential applications despite their strong absorbing properties. Conveniently, to address this issue many carbonaceous materials such as carbon nanotubes (CNTs), carbon laments, carbon bers and chemically derived graphene have been used as composite materials for electromagnetic-wave absorbers owing to their light weight, exibility, high thermal conductivity, excellent mechanical properties and high electrical conductivity.…”

“…Table 3 shows the microwave absorption properties of other Fe 3 O 4 -carbon-based composites. 5,13,[54][55][56] It can be seen that this kind of newly fabricated Fe 3 O 4 /WPC-600 composites can be regarded as promising candidates for high-performance microwave-absorbing materials.…”