Electromagnetic Wave Absorption Performance of Co₃Fe₇/Melamine Sponge Carbon Composites

In situ formed Co₃Fe₇ loading on carbon foams can weaken the weight of the absorbers. In this work, a CoFe metal-organic framework (MIL-88A) precursor was assembled to a melamine sponge (MS) via hydrothermal method. Subsequent calcination led to the decomposition of spindle-shaped CoFe-MOF and formation of Co₃Fe₇ nanoparticles on the 3D hollow sponge-derived carbon (MS/Co₃Fe₇). Furthermore, by varying the Co₃Fe₇ loading, the electromagnetic wave (EMW) absorption performances were tuned. Notably, the MS/Co₃Fe₇-50 composite exhibited the best performance: A minimum reflection loss (RL) of -17.03 dB was obtained at a thickness of 2.60 mm and a frequency of 13.12 GHz, while the effective absorption bandwidth (EAB) reached 3.28 GHz within the range of 10.08 to 13.36 GHz. This outcome is mainly related to the hollow architecture that extends the propagation path of EMWs, the coordinated interaction between polarization and magnetic loss mechanisms, and the well-balanced electromagnetic impedance. Consequently, the MS/Co₃Fe₇ composite presents a promising way for the design of lightweight, highly efficient EMW absorption materials.