Composition Design and Structural Characterization of MOF-Derived Composites with Controllable Electromagnetic Properties

Simply and effectively achieving the tunability of the composition and chemical state of each component remains a challenge for modifying the electromagnetic performance of metal-organic-framework-derived (MOF-derived) composites. In this work, quaternary ZnO/Fe/Fe3C/carbon composites have been successfully synthesized by thermal decomposition of Fe-III-MOF-5. The composition and chemical state of each component can be effectively controlled by changing the heating temperature. In detail, with increasing temperature, the Fe element would be transformed from Fe3+ to Fe3C and Fe, which also leads to the graphitization and weight loss of carbon. The effects on electromagnetic properties are also investigated, and the ZFC-700 sample possesses optimized reflection loss (RL) performance with an RL value of 30.4 dB and a broad effective frequency bandwidth of 4.96 GHz at a thin thickness of only 1.5 mm. Conduction loss, interfacial polarization, ferromagnetic resonance, and interference cancelation should be responsible for ideal electromagnetic absorption. The porous quaternary composites not only convert incident electromagnetic energy to heat rather than reflect it back which is in favor of solving electromagnetic pollution, but also reduce the consumption of the metal source and poisonous raw materials for traditional microwave-absorbing materials.