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

Abstract

Metal-organic compounds derived composites are promising multi-functional materials due to their alterable composition, tunable shape, and porous structure. However, it is very attractive and 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) through heat treatments of a Co-based metal-organic precursor under different temperatures, exhibiting the wideband and strong EWA performance. The three-dimensional urchin-like porous structure can not only promote the electromagnetic wave propagation and attenuation, but also enhance the surface polarization relaxation. As a result, this kind of urchin-like morphology leads to the exceptional interface polarization loss and impedance matching, affording a wide absorption bandwidth exceeding 7 GHz. Among these materials, Co/C-550 demonstrates the outstanding performance, affording an effective absorption bandwidth of 7.92 GHz under 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 urchin-like morphology, porous structure, dielectric and magnetic losses. This work provides some guidance for the design of light and thin electromagnetic wave absorption materials with wide absorption bandwidth.