Ordered Mesoporous\nMultishell Composite Microspheres\nwith Controlled Loading of Magnetic Particles for Enhanced Electromagnetic\nWave Absorption Performance

Precise\nconstruction of rational structures and optimization of\nmaterial components are the main strategies for the design and preparation\nof novel high-performance electromagnetic wave (EMW) absorbers. Here,\nSiO<sub>2</sub>/RF@m-PDA multishell composite microspheres with an\nordered mesoporous structure are produced by a two-step reaction of\nsimultaneous hydrolysis precipitation polymerization and dopamine\nself-polymerization with a soft stencil method. The microspheres are\nmonodisperse with an average particle size of 380 nm. Then magnetic\nCo nanoparticles are embedded inside the mesoporous pores using an\nimpregnation reduction method, which allows the preparation of SiO<sub>2</sub>/C/NC-Co composite EMW absorbers with different magnetic component\nloadings. The effective absorption bandwidth of SiO<sub>2</sub>/C/NC-Co-2\nreaches 7.36 GHz at a thickness of 2.2 mm, and the minimum reflection\nloss reaches −46.59 dB by adjusting the filling load of the\nEMW absorber. The excellent electromagnetic wave absorbing performance\nis attributed to the dual loss mechanism and synergistic effect of\nthe magnetic/dielectric and the abundant heterogeneous interfaces\ngiven by the multishell layer and mesoporous structure. This study\nprovides a feasible method to prepare complex structures with multicomponent\ndoped magnetic composite EMW absorbers.