Construction of urchin-like porous Co/CoO/C composites enabling high-performance wideband electromagnetic wave absorption

Abstract

Metal–organic compound derived composites are promising multi-functional materials owing to their adjustable composition, tunable shape and porous structure. However, it is very attractive but challenging to design light and thin composites derived from metal–organic compounds with broad and strong electromagnetic-wave absorption (EWA). Herein, we designed and synthesized a series of urchin-like porous structures (CoO/C-450, CoO/C-500, Co/C-550 and Co/C-600) with wideband and strong EWA performance through heat treatments on a Co-based metal–organic precursor at different temperatures. The three-dimensional urchin-like porous structure can not only promote electromagnetic wave propagation and attenuation, but also enhance surface polarization relaxation. As a result, this kind of urchin-like morphology leads to exceptional interface polarization loss and impedance matching, affording a wide absorption bandwidth exceeding 7 GHz over X and Ku bands. Among these materials, Co/C-550 demonstrates an outstanding performance, affording an effective absorption bandwidth of 7.92 GHz with a low thickness of 2.5 mm and a minimum reflection loss of −51.2 dB. The remarkable EWA performance was mainly attributed to the synergistic effect of the urchin-like morphology, porous structure, and dielectric and magnetic losses. This work provides some guidance for the design of light and thin electromagnetic wave absorption materials with a wide absorption bandwidth.