Reduced graphene oxide-wrapped Fe-Fe3O4@mSiO2 hollow core-shell composites with enhanced electromagnetic wave absorption properties

The Fe/Fe3O4 nanocomposite with mesoporous silica (mSiO(2) for short) shell was successfully prepared by solvothermal reaction combined with hydrogen-thermal annealing (550 degrees C). Further, reduced graphene oxide (RGO) was introduced to obtain Fe-Fe3O4@mSiO(2)@RGO hollow core-shell composites with hollow structure by an aerogel method utilizing home-made equipment. The introduction of mSiO(2) on the surface of Fe3O4 created a ventilated framework, which maintained the dispersion of fine Fe particles emerging from the reduction process. The transformation from Fe3O4 to Fe nanoparticles enhanced the ferromagnetic loss, while the introduction of high conductivity RGO also enhanced the polarization relaxation and conductivity loss. Meanwhile, the unique hollow structure of the core-shell structure effectively reduced the density of the ferromagnetic composites (Fe-Fe3O4@mSiO(2)) without sacrificing the contact between RGO and nanoparticles, adding more surfaces/interfaces. Fe-Fe3O4@mSiO(2)@RGO exhibited excellent electromagnetic wave absorption properties. The coating using Fe-Fe3O4@mSiO(2)@RGO as fillers exhibited a minimum reflection loss of -66.24 dB with an effective absorption bandwidth of 5.31 GHz with a sample thickness of only 1.79 mm. The hollow core-shell structure of RGO-wrapped Fe-Fe3O4@mSiO(2) demonstrates a promising approach for the design of lightweight and high-performance electromagnetic absorption materials.

Automated summary

The Fe/Fe3O4 nanocomposite with mesoporous silica shell was successfully prepared, and further, reduced graphene oxide was introduced to obtain Fe-Fe3O4@mSiO(2)@RGO hollow core-shell composites. The introduction of mSiO(2) and RGO improved the electromagnetic wave absorption properties of the composites. The hollow core-shell structure demonstrated a promising approach for the design of lightweight and high-performance electromagnetic absorption materials.