Confined assembly of magnetic Fe₃O₄/carbon microspheres with enhanced wave absorption performance

The escalating use of electronic devices in civil and military sectors has led to severe electromagnetic interference issues due to excessive electromagnetic radiation, impacting both equipment functionality and human well-being. Addressing this, electromagnetic wave absorption materials, particularly magnetic carbon superstructures, offer a dual loss mechanism suitable for microwave absorption, gaining much attention. In this work, through a polyelectrolyte-assisted assembly strategy, magnetic carbon superstructures (MCSSs) with high performance characteristics such as ultra-wide effective absorption bandwidth and minimal reflection loss have been developed. Detailed structural analyses through microscopy, XRD, elemental analysis, and magnetic studies confirm the successful synthesis of MCSSs with hierarchically porous structures, high specific surface areas of 476.6 m² g⁻¹, total pore volume of 0.27 cm³ g⁻¹, and notable ferromagnetic properties. Each independently existing spherical MCSSs can be viewed as a separate confined space, in which well-dispersed homogeneous magnetic particles exist, which greatly improves the undesirable condition of local impedance matching imbalance caused by agglomeration of magnetic components due to intrinsic magnetic properties. Finally, the MCSSs hold excellent microwave absorption of −62.23 dB and radar cross section attenuation of 16.80 dB m². These findings underscore the potential of magnetic carbon superstructures in advancing electromagnetic wave absorption technologies and highlight the importance of tailored design for optimizing material properties.