MnO₂-coated necklace-like CoFe@carbon nanofiber composites for superior electromagnetic wave absorption

With the rapid development of modern electronic technology, electromagnetic wave (EMW) absorption materials play a crucial role in solving the problem of electromagnetic radiation pollution. By designing unique microstructures or composite magnetic components, the EMW attenuation ability of carbon nanofibers (CNFs) can be enhanced. However, the ultra-high conductivity of CNFs leads to impedance mismatch, necessitating the introduction of components that can rapidly optimize dielectric properties for improved impedance matching. In this study, Co_0.7Fe_0.3@CNFs@MnO₂ (CFCM) was fabricated by coating MnO₂ nanosheets on necklace-like CoFe@carbon nanofiber composites. The coated MnO₂ nanosheets not only enhance the EMW attenuation ability, but also improve impedance matching. The results indicate that the minimum reflection loss of the sample is -62.7 dB, and the effective absorption bandwidth reaches 6.5 GHz. This work presents a valuable method to prepare outstanding EMW absorption materials with a necklace-like 3D network hierarchical structure.