Constructing FeCo@C core-shell structure with strong polarization behavior towards excellent microwave absorption performance

In this study, the electromagnetic wave absorption properties of derivatives of metal-organic frameworks (Prussian blue analogues) were investigated. Here, we use the co-precipitation method to combine metal ions (Mn2+, Ni2+, Co2+) with potassium ferricyanide to obtain cubic precursors. Subsequently, a series of carbon-coated bimetallic alloy absorbers with a core-shell structure were obtained by pyrolysis in a vacuum thermal environment. Moreover, the effect of temperature on the structure and electromagnetic absorption properties of FeCo@C was further explored. FeCo@C-600 achieves an effective bandwidth of 5.63 GHz at a thickness of 1.8 mm, and the minimum reflection loss is as high as −66.69 dB. Its best microwave absorption performance comes from the polarization sites provided by the abundant heterogeneous planes and defects, enabling it to obtain enhanced polarization loss. The final results show that the method of optimizing performance by enriching polarization methods can provide a new idea for obtaining high-efficiency absorbing materials with thin thickness and wide frequency coverage.