Establishment of 3D hollow tubular/spherical Fe3O4/MWCNTs/solid waste composites for enhanced electromagnetic absorbing property

Nowadays, high-efficiency electromagnetic wave absorption (EWA) materials with simple preparation techniques are desirable for practical applications. However, there are many obstacles need to be overcome. In this work, a novel 3D hollow tubular/spherical structure system has been established by using Fe 3 O 4 as a magnetic loss component, MWCNTs as a dielectric loss component, fly ash cenospheres (FACs) as a structural skeleton through simple self-assembly to achieve excellent EWA properties. Particularly, FACs which derive from power plant solid waste are hollow and insulating that help to regulate the electromagnetic parameters, the conductivity, and the impedance matching characteristics of the composites, as well as reduce the cost. The effect of the unique heterogeneous structure with multiple interfaces on the EWA performance is investigated. The superior absorption performance is primarily due to the synergistic effect of component design and the unique tubular/spherical structure, which provide efficient interfacial polarization loss, dipole polarization loss, moderate conductive loss, good impedance matching, and a large transmission route. The effective absorption bandwidth is as wide as 3.8 GHz at a thickness of 2.0 mm, and the RL min value is −47.35 dB at a thickness of 3.0 mm. The prepared Fe 3 O 4 /MWCNTs/FAC composites have excellent EWA properties that are superior to the majority of recently reported comparable composites. The product meets the requirements of high absorption performance, simple preparation, stable structure, low cost and environmental friendly, which greatly improves its applicability.