PANI/FeCo@C composite microspheres with broadband microwave absorption performance

Abstract Composite microwave absorbers with multiple loss mechanism have attracted more and more attention. Herein, we report a strategy of step-by-step synthesis of polyaniline (PANI)/FeCo@C composite microspheres by hydrothermal, calcination and in-situ polymerization. The multilayer heterogeneous interfaces of microspheres and the multi dipole center of polyaniline molecular chain significantly improve the polarization relaxation loss. Polyaniline on the surface connects the microspheres to form a conductive network, which effectively enhances the conduction loss. FeCo alloy particles also provide a certain magnetic loss. Their synergistic effect makes the composite microspheres exhibit good microwave absorption performance. When the thickness of P2 is only 1.7 mm, it could exhibit an effective absorption bandwidth (EAB) of 5.31 GHz and maximum reflection loss (RL) of −33.86 dB. Moreover, we optimized the macro structure of the absorber through gradient design, and successfully extended the effective absorption bandwidth to 11.81 GHz by introducing multiple interference. This work provides a useful reference for the comprehensive optimization of micro regulation and macro design of composite microwave absorbers.