Hierarchical nest-like structure of Co/Fe MOF derived CoFe@C composite as wide-bandwidth microwave absorber

Recently, metal-organic frameworks (MOFs) derived carbonaceous materials have attracted much interest as prospective microwave absorbers due to their porous structure, aperture adjustable, and topological diversity. Herein, a facile strategy was developed to regulate the morphology of CoFe-MOF-74 by adjusting the molar ratio of Co/Fe, and the hierarchical nest-like structure consisted of a large number of CoFe-MOF-74 nanorods was formed as the molar ratio of Co/Fe was 3:1. After pyrolysis at 800 degrees C in an argon atmosphere, porous CoFe@C nanorod-built hierarchical nest-like structures were obtained, which displayed superior microwave absorption performance with low filler loading of 10 wt%. The maximum reflection loss (RL) was -61.8 dB at 12.7 GHz with a thickness of 2.8 mm, and the corresponding effective absorbing bandwidth (RL < -10 dB) reached up to 9.2 GHz (8.8-18.0 GHz). The improved impedance matching, multi-scale pore structure, multiple reflections and scattering endowed by unique hierarchical nest-like structure, would contribute to the excellent microwave absorbing properties. Our research might provide a new direction to the fabrication of carbon-based absorber derived from MOFs with excellent microwave absorbing properties at low filler loading.