Synthesis of Fe₃O₄/SiO₂ nanocomposites via click chemistry and electromagnetic wave absorption properties

Fe₃O₄/SiO₂ nanocomposites (NCs) were prepared by the interaction of alkyne-functionalized ferric oxide (Fe₃O₄-Alk) nanoparticles (NPs) and azide-functionalized silicon dioxide (SiO₂-N₃) NPs via the click reaction. The morphology and structure of the Fe₃O₄/SiO₂ NCs were investigated using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and infrared analyses, and the electromagnetic parameters were measured using a vector network analyzer. For the Fe₃O₄/SiO₂ nanocomposites obtained via the click reaction, the minimum reflection loss reached − 37.15 dB at 16.68 GHz and a matching thickness of 5.0 mm, and the bandwidth below − 10 dB ranged from 3.2 to 6.7 GHz and 15.7 to 17.6 GHz. The Fe₃O₄/SiO₂ composites synthesized via the click reaction exhibited better microwave absorption performance than the physically blended sample. This is mainly because Fe₃O₄ and SiO₂ are covalently bonded through the click reaction in the composites, creating multiple heterogeneous interfaces, which enhance dielectric loss and impedance matching.