Hollow multi-shell SiC@C@PANI nanoparticles with broadband microwave absorption performance

The hollow multi-shell structure has been used as a basic concept for the design and preparation of microwave absorbing (MA) materials. Herein, we prepared novel hollow SiC@C@PANI (SCP) nanoparticles by a two-step in situ polymerization method, template method and carbon thermal reduction method. By coating different pro-portions of polyaniline (PANI) on the surface of SiC@C microspheres to regulate the impedance matching and reduce the escape of electromagnetic waves, the suitable dielectric loss and impedance matching reach an optimal balance, the multilayer heterogeneous interface significantly improves the polarization relaxation behavior, and the hollow structure enhances the multiple reflections and scattering of electromagnetic waves. Finally, the effective absorption bandwidth (EAB) of SCP-1:1.5 reached 5.61 GHz at only 1.88 mm. Moreover, we designed and optimized the macroscopic structure of the MA metamaterial through gradient modulation, and successfully broadened the EAB to 10 GHz by introducing multiple interferences, which completely covers the X, Ku bands. Simultaneous optimization strategies for microscopic design and macroscopic regulation of hollow multi-shell absorbers provide ideas for breaking the performance boundaries of MA materials.