Fe₃O₄ Nanoflower-Carbon Nanotube Composites for Microwave Shielding

Unsatisfactory reflection loss (RL) and thick thickness of the absorber severely limit the practical application of advanced electromagnetic (EM) microwave absorbers. Herein, we report a heterogeneous architecture that consists of Fe3O4 nanoflower, which construct from ultrathin nanosheets, and carbon nanotubes (CNTs) backbone to enhance their RL in low-thickness regions. Thanks to the reasonable structural design and dielectric loss regulation, the optimized Fe3O4/CNTs composites exhibit superior microwave absorbing properties. The minimal RL is −58.6 dB at 15.28 GHz. Meanwhile, the thickness is only 1.52 mm. Furthermore, when RL is below −10 dB, the actual absorption bandwidth is as high as 15 GHz at absorber thickness below 5 mm. The effective permeability (μr), permittivity (εr), and Z values indicate that the remarkable microwave absorption is attributable to the coordination of the excellent polarization relaxation of CNTs, the good intrinsic magnetic properties of Fe3O4 nanoflower, and the abundant interfacial polarization between Fe3O4 and CNTs.