ZnO Nanorod-Based Microflowers Decorated with Fe₃O₄ Nanoparticles for Electromagnetic Wave Absorption

It is of great significance to improve the electromagnetic wave absorption performance of absorbing materials for application in critical fields using different techniques to design a unique structure. Three-dimensional (3D) ZnO nanorods with unique microflower-like structures and high-performance microwave absorption were successfully synthesized via the hydrothermal route and annealing process, which were modified with sphere-like Fe3O4 nanoparticles. The composites display an outstanding microwave absorption property with different contents of Fe3O4 nanoparticles and the mass ratio of ZnO/Fe3O4 to paraffin is 3:2. The best reflection loss (RL) value can reach −36.2 dB at 9.35 GHz with an absorber thickness of only 2.7 mm and the corresponding absorption bandwidth is 4.02 GHz (6.81–10.83 GHz) in the range of 2–18 GHz when the composites contain 11.3 wt % Fe3O4 as the filler. A mechanism is proposed and discussed to further understand the absorption behavior of composites. This work demonstrates a promising synthetic route to design thin, economical, and wide-bandwidth stable microwave-absorbing materials with outstanding microwave absorption performance.