Lightweight three-dimensional Fe3O4/carbon micro-flowers with tunable microwave absorption properties

Abstract Fe 3 O 4 /C micro-flowers with a three-dimensional (3D) porous morphology (3D-Fe 3 O 4 /C MFs, ∼5–7 μm) were prepared by a simple hydrothermal method, with a subsequent calcination step. The 3D-Fe 3 O 4 /C MFs consisted of radially assembled 2D Fe 3 O 4 /C nanoflakes (NFs, thickness ∼40 nm). When the electromagnetic wave absorption (EMWA) performances of paraffin composites with 10, 30, and 40 wt% 3D-Fe 3 O 4 /C MF loading and Fe 3 O 4 -based materials were compared, the paraffin composite with 20 wt% loading exhibited a strong reflection loss (RL, −37.6 dB) and a broad effective absorption bandwidth (EAB, RL  3 O 4 ), combined with a hierarchically porous and 3D structure. The lightweight and broad EAB and the strong and tunable EMWA performances of 3D-Fe 3 O 4 /C MFs make them attractive for the development of high-performance EMW absorbers.