Ordered Mesoporous Multishell Composite Microspheres with Controlled Loading of Magnetic Particles for Enhanced Electromagnetic Wave Absorption Performance

Precise construction of rational structures and optimization of material components are the main strategies for the design and preparation of novel high-performance electromagnetic wave (EMW) absorbers. Here, SiO₂/RF@m-PDA multishell composite microspheres with an ordered mesoporous structure are produced by a two-step reaction of simultaneous hydrolysis precipitation polymerization and dopamine self-polymerization with a soft stencil method. The microspheres are monodisperse with an average particle size of 380 nm. Then magnetic Co nanoparticles are embedded inside the mesoporous pores using an impregnation reduction method, which allows the preparation of SiO₂/C/NC-Co composite EMW absorbers with different magnetic component loadings. The effective absorption bandwidth of SiO₂/C/NC-Co-2 reaches 7.36 GHz at a thickness of 2.2 mm, and the minimum reflection loss reaches −46.59 dB by adjusting the filling load of the EMW absorber. The excellent electromagnetic wave absorbing performance is attributed to the dual loss mechanism and synergistic effect of the magnetic/dielectric and the abundant heterogeneous interfaces given by the multishell layer and mesoporous structure. This study provides a feasible method to prepare complex structures with multicomponent doped magnetic composite EMW absorbers.