Synthesis of three-dimensional carbon networks decorated with Fe3O4 nanoparticles as lightweight and broadband electromagnetic wave absorber

Abstract Three-dimensional (3D) carbon networks decorated with Fe3O4 nanoparticles as lightweight and broadband electromagnetic (EM) wave absorber were in-situ prepared via a simple and large-scale method, combining freeze-drying and high-temperature calcination processes. SEM and TEM results show that 3D carbon network/Fe3O4 (3DC/Fe3O4) composites have interconnected 3D porous carbon networks with submicrometer-sized macropores, and the Fe3O4 nanoparticles are distributed uniformly on the 3D carbon networks. The EM wave absorption performance of 3DC/Fe3O4 can be tuned by changing Fe3O4 contents. The 3DC/Fe3O4 with about 38.2 wt% Fe3O4 exhibits excellent lightweight and broadband EM wave absorption property. The effective absorption bandwidth can reach up 5.95 GHz (11.2–17.15 GHz) at the thickness of 3.0 mm with only 20 wt% filler loading. The minimum RL of −37.8 dB was obtained at 6.95 GHz. The excellent EM wave absorption capability of 3DC/Fe3O4 can be ascribed to good impedance matching, strong dielectric loss ability and unique 3D porous structure. This work demonstrates that the 3DC/Fe3O4 with light weight, broad absorption bandwidth and large-scale production potential can be a promising absorber for practical application.