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

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. A series of urchin-like porous Co/CoO/C composites with wideband and strong EWA performance have been prepared, in which the 3D porous urchin-like microstructures facilitate the propagation and attenuation of electromagnetic waves.