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Complementary design of nano-carbon/magnetic microwire hybrid fibers for tunable microwave absorption

Estevez, D., Qin, F.X., Quan, L., Luo, Y., Zheng, X.F., Wang, H., Peng, H.X.
Carbon 2018 v.132 pp. 486-494
absorption, annealing, assets, carbon nanotubes, graphene, graphene oxide, magnetism, metals, moieties
Hybridizing nanocarbons, such as carbon nanotubes (CNT) or graphene, with magnetic metals is a powerful strategy towards designing high-performance microwave absorber due to the resulting synergetic loss mechanisms and tunable electromagnetic properties. Herein, CNT and reduced graphene oxide (rGO) have been respectively coupled with amorphous wire through electrodeposition in a complementary fashion. The absorption performance of the hybrid fibers proves to be tunable via controlling the thickness and morphology of the CNT or by regulating the number of oxygen-functional groups of rGO through thermal annealing. The CNT/wire hybrid structure effectively strengthens both the interfacial polarization of CNT through the support of circular-shaped conductive substrate, and the ferromagnetic resonance of wire through the coupling with magnetic impurities in CNT. As for the rGO/wire fiber, dual-band absorption occurs in the sample annealed at 900 °C with an optimal absorption loss of −35 dB at 11.3 GHz, derived from dielectric loss mechanisms such as removal of functional groups and induced defective structure in combination with enhanced magnetic losses in the hybrid structure. Such complementary design opens up new horizons to scale up the excellent assets of nano-carbons into the macroscale and develop functional adaptive materials for high-frequency applications.