Synergistic microstructure of sandwich-like NiFe2O4@SiO2@MXene nanocomposites for enhancement of microwave absorption in the whole Ku-band

Recently, thin, lightweight, wide and strong microwave absorption performance are the main targets for researchers to design high-performance absorbers. A new two-dimension MXene material has attracted significant attention because of its unique hierarchical structure, large specific surface area and special metallic features. However, its improperly high electrical conductivity of MXene causes the bad microwave absorption performance. To meet the needs of practical application, the sandwich-like NiFe2O4@SiO2@MXene nanocomposites were fabricated via multilayered MXene and core-shell NiFe2O4@SiO2 nanoparticles. By the synergistic effects from the SiO2 (transparent medium) improving impedance matching and the two-dimensional laminated MXene increasing conductive loss, the microwave absorption performance of NiFe2O4@SiO2@MXene can be effectively regulated and optimized. As a result, the minimum reflection loss of NiFe2O4@SiO2@MXene reaches −52.8 dB at 11.6 GHz with a thickness of 2 mm, and the maximum effective absorption bandwidth is 7.2 GHz (10.8–18 GHz) covering the whole Ku-band with only a 1.5 mm thickness. It has proved that microcosmic sandwich-like structure design is an efficient approach to achieving excellent microwave absorption performance. The multiple components and unique structure generate heterogeneous interfaces, multiple reflections, polarization features and well-matched impedance. This work provides an insight for rationally constructing hybrid materials with a complex structure in the application of microwave absorption field.