Facile fabrication of hierarchical flowerlike γ-AlOOH hollow spheres decorated with MWCNTs for electromagnetic wave absorption

To explore a type of high-performance microwave absorber with lightweight and thin thickness, the flowerlike γ-AlOOH hollow spheres decorated with multi-walled carbon nanotubes (MWCNTs) were fabricated by a facile hydrothermal method. The microscopic morphology characterization showed the γ-AlOOH microspheres consisted of a hollow inner core and a shell made of numerous flakes. The γ-AlOOH/MWCNTs composites exhibited excellent microwave absorption performance with the reflection loss of − 49.8 dB at 11.1 GHz and effective absorption bandwidth of 4.56 GHz (from 13.44 to 18 GHz) at a thickness of 1.5 mm, which covered almost the entire X band. Furthermore, the unique microstructure of γ-AlOOH exerted a considerable effect on the obtained microwave absorption capacity of the composites, leading to interfacial polarization, multiple reflections, and scattering of electromagnetic wave. Meanwhile, the suitable MWCNTs additive amount played a crucial role in the improvement of impedance matching, conduction loss, and dipole polarization, which benefit the performance of microwave absorption. It is expected that the flowerlike hollow spheres structure in our work can provide a method of designing the novel microwave absorbers.