Construction of flexible magnetic carbon nanofibers by core-shell MOF derivatives for optimizing microwave absorption

Although carbon fibers have significant dielectric loss, poor impedance matching often results in a narrow effective absorption bandwidth, which in turn induces unsatisfactory microwave absorption (MA). The composition and microstructure are remarkably critical factors in order to optimize the MA performance. Herein, the flexible magnetic carbon nanofibers (CoFe@CNFs) were prepared based on one-dimensional carbon nanofibers and core-shell MOF derivatives by electrospinning technology and subsequent high-temperature heat treatment. The integration of core-shell ZIF-67@ CoFe-PBA derivatives, the three-dimensionalconductive network of carbon nanofibers and the synergistic magnetic loss and dielectric loss significantly optimizes the impedance matching, which enables the CoFe@CNFs to simultaneously achieve favorable MA performance and lightweight characteristics. The CoFe@CNFs show a minimum reflection loss value of -47.9 dB and the maximum effective absorption bandwidth of 6.5 GHz when the filling ratio is only 7.5 wt%. In addition, the complex composition and unique microstructure endow the composites with excellent flexibility. This work provides a meaningful guidance for constructing lightweight MA materials with broadband absorption characteristics.