Hybrid inorganic-organic capsules encapsulated FeNi with enhanced corrosion resistance and microwave absorption

Responding to the critical need for stable microwave absorption (MA) devices in complex and extreme environments, dual-function electromagnetic wave absorbers have garnered significant attention. Addressing this, we developed a novel FeNi-based composite encapsulated within superhydrophobic SiO 2 @Perfluorooctyltriethoxysilane (F13)/Methyltrimethoxysilane (MTMS) hybrid capsules, approximately 28-nm-thick, utilizing a straightforward one-pot strategy. This innovative FeNi@SiO 2 @F13/MTMS composite surpassed pure FeNi, exhibiting an effective MA bandwidth of 8.16 GHz and a minimal reflection loss value of −24.03 dB at 2.00 mm. It also boasted the largest radar scattering cross-section reduction value recorded at 21.09 dB m 2 . The enhanced MA properties were primarily attributed to the SiO 2 @F13/MTMS, which significantly improved the substrate's impedance matching. In addition to facilitating multiple scattering and reflection, it also triggered dipole and interfacial polarization. Moreover, the SiO 2 @F13/MTMS layer was instrumental in reducing the corrosion current density of FeNi from 3.512 mA cm 2 to 5.59 nA cm 2 , thereby demonstrating exceptional corrosion resistance. This remarkable improvement was largely due to the surface hydrophobicity and the barrier effect provided by the hybrid capsules. Our exploration into corrosion-resistant and efficient MA materials provides valuable insights for the rational design of bifunctional components tailored for specific applications.