Enhanced electromagnetic wave absorption of hybrid-architectures Co@ SiOxC

Abstract

Rational design on the well wrapped core-shell microstructure of Co@ SiO x C composites was successfully conducted through reduction process of cobalt, efficient condensation reaction of KH-550 silane coupling agent as well as high temperature calcination. The SiO x C shell possessed 3D cross-linked network structure consisting of dielectric carbon and silicon composition for optimal electromagnetic matching. The microstructure, morphology, elements distribution, electromagnetic property and microwave absorption performance were fully characterized, respectively. This SiO x C shell effectively inhibited the agglomeration of cobalt particles, and regulated the complex electromagnetic parameters by decreasing permittivity and introducing polarization relaxation, all of which determined the efficient reflection loss with RL min value of −60.3 dB at 16.2 GHz and matching thickness of only 2.05 mm. Meanwhile, the effective absorption band is up to 7.1 GHz at 2.3 mm. By optimizing of core-shell structure and material components, the high-absorption performance was obtained through impedance matching, multi-interfacial polarizations, dipole (or defects) polarization and magnetic loss. Therefore, the Co@ SiO x C composites present a facile and promising route toward the design of large-scale-preparation and excellent microwave absorbing materials. • First use KH-550 as a preliminary coating toward core-shell absorber. • The EAB of Co@SiO x C composites is of 7.1 GHz and RL min is up to −60.3 dB at 2.05 mm. • It is convenient to synthesize.