MOF-derived magnetic-dielectric balanced Co@ZnO@N-doped carbon composite materials for strong microwave absorption

Abstract

Composite materials with magnetic and dielectric properties are considered as promising candidates for electromagnetic wave absorbing materials. However, adjusting the electrical and magnetic properties of materials at the same time faces a huge challenge. Here, using metal organic frameworks (MOFs) as the precursors, highly dispersed Co and ZnO nanoparticles are uniformly confined in the graphitized nitrogen-doped carbon framework, building a balanced electromagnetic performance in the absorbent. Meanwhile, by adding template agents and changing the metal source, the shape of metal/carbon-based materials derived from mostly controllable MOFs has realized the transformation from six-pointed star, flower-like, cube-like to random stone-like. Thanks to its special morphology and balanced magnetic dielectric multiloss mechanism, the six-pointed star Co@ZnO@NC-a exhibits a minimum reflection loss (RLmin) of −61.9 dB at 8.7 GHz and the effective absorption bandwidth (EAB) is 5.5 GHz (11.6–17.1 GHz) at 2.3 mm thickness. These results provide a new design strategy for fabricating high performance magnetic dielectric absorbing materials with special morphology.