Covalently bonded Fe₃O₄@SiO₂−reduced graphene oxide nanocomposites as high-efficiency electromagnetic wave absorbers

A novel electromagnetic (EM) wave absorber is synthesized by covalently modifying reduced graphene oxide (rGO) with Fe₃O₄@SiO₂ nanoparticles. The results show that after the amidation reaction, magnetic Fe₃O₄@SiO₂ nanoparticles are successfully linked to rGO via amide bonds. The EM wave absorption properties can be adjusted by changing the weight ratio of Fe₃O₄@SiO₂ to rGO. When the ratio is 1:1, the absorber exhibits outstanding absorption performance that the maximum reflection loss (RL) peaks achieve −55.4 dB at 8.48 GHz, −55.4 dB at 8.08 GHz and −52.5 dB at 7.2 GHz with matching thicknesses of 3.5 mm, 3.7 mm and 4.0 mm. The excellent absorption performance can be attributed to good impedance matching and superior attenuation ability. The introduction of amide bonds can act as carrier channels to promote the migration of electrons, change the electron cloud distribution of graphene and adjust EM parameters of absorbers to achieve excellent absorption properties. It provides a new approach to prepare high-efficiency EM wave absorbers.