Construction of cobalt zinc metal-organic frameworks derived Co/CoO/C composites toward broadband and high-efficiency electromagnetic wave absorption

Abstract

The fabrication of novel carbon-based electromagnetic wave (EMW) absorbers with broad absorption bandwidth, strong absorption strength, low filler loading ratio and thin matching thickness remains a challenging task. Metal-organic frameworks (MOFs) are widely recognized as ideal self-sacrificial templates for the construction of carbon-based EMW absorbers. In this work, bimetallic CoZn-MOFs derived Co/CoO/C composites were prepared by combining magnetic stirring with subsequent pyrolysis treatment. The results showed that the morphology of carbon skeletons evolved from an irregular agglomerate to a uniform hexagonal star shape and then to an agglomerate again by reducing the molar ratio of Co2+ to Zn2+. Remarkably, excellent EMW absorption capacity in the Ku-band was achieved through carefully regulating the molar ratio of Co2+ to Zn2+. When the filling ratio was 20wt.%, the prepared Co/CoO/C composite exhibited the best EMW absorption performance with the minimum reflection loss of -64 dB at a thickness of 1.79mm and the maximum effective absorption bandwidth of 6GHz at a thickness of 2.14mm. Furthermore, the radar cross section in the far-field was simulated by computer simulation technique. In addition, the possible EMW attenuation mechanism was proposed. Therefore, the results of this paper could be helpful for developing carbon-based magnetic composites derived from MOFs as broadband and high-efficiency EMW absorbers.