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

Three-dimensional (3D) carbon networks decorated with Fe 3 O 4 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/Fe 3 O 4 (3DC/Fe 3 O 4 ) composites have interconnected 3D porous carbon networks with submicrometer-sized macropores, and the Fe 3 O 4 nanoparticles are distributed uniformly on the 3D carbon networks. The EM wave absorption performance of 3DC/Fe 3 O 4 can be tuned by changing Fe 3 O 4 contents. The 3DC/Fe 3 O 4 with about 38.2 wt% Fe 3 O 4 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/Fe 3 O 4 can be ascribed to good impedance matching, strong dielectric loss ability and unique 3D porous structure. This work demonstrates that the 3DC/Fe 3 O 4 with light weight, broad absorption bandwidth and large-scale production potential can be a promising absorber for practical application.