Hierarchical multi-shell hollow porous NiO/Co3O4 nanospheres with enhanced dielectric-magnetic synergy for high-efficiency microwave absorption

In response to the increasing challenges posed by electromagnetic pollution, The development of high-performance microwave absorbing materials is increasingly urgent. This study addresses this challenge through synergistic engineering of hierarchical architectures and magnetic-dielectric components, proposing a sequential templating strategy to fabricate hierarchical multi-shell hollow porous (HMSHP) NiO/Co 3 O 4 nanospheres. Systematic characterization reveals that the HMSHP architecture can effectively improve the impedance matching, reduce the material density, extend the microwave transmission path, and significantly enhance the conduction loss and interface polarization loss. In addition, the NiO/Co 3 O 4 heterointerfaces induce polarization loss caused by lattice defects in the shell and magnetic loss due to the magnetic metal oxide components, which synergistically enhance electromagnetic energy conversion. The 3-shell hollow porous NiO/Co 3 O 4 nanospheres (3-NCO) demonstrated superior microwave absorption performance. Specifically, at a low filler ratio (20 wt%) and a thin thickness (2.1 mm), the 3-NCO nanospheres exhibited a significant absorption capacity (−67.62 dB) and a wide effective absorption bandwidth (7.68 GHz). This work reveals a nanostructure design route for designing lightweight, broadband microwave absorbers through rational integration of structural hierarchy and interfacial engineering, offering actionable strategy to fabricating novel microwave absorption nanomaterials.