Synthesis of covalently bonded reduced graphene oxide-Fe₃O₄ nanocomposites for efficient electromagnetic wave absorption

High-performance electromagnetic (EM) wave absorbers, covalently bonded reduced graphene oxide-Fe₃O₄ nanocomposites (rGO-Fe₃O₄), are synthesized via hydrothermal reaction, amidation reaction and reduction process. The microstructure, surface element composition and morphology of rGO-Fe₃O₄ nanocomposites are characterized and corresponding EM wave absorption properties are analyzed in great detail. It demonstrates that Fe₃O₄ nanoparticles are successfully covalently grafted onto graphene by amide bonds. When the mass ratio of rGO and Fe₃O₄ is 2:1 (sample S2), the absorber exhibits the excellent EM wave absorption performance that the maximum reflection loss (RL) reaches up to -48.6 dB at 14.4 GHz, while the effective absorption bandwidth (RL<-10 dB) is 6.32 GHz (11.68–18.0 GHz) with a matching thickness of 2.1 mm. Furthermore, radar cross section (RCS) simulation calculation is also adopted to evaluate the ability of absorbers to scatter EM waves, which proves again that the absorption performance of absorber S2 is optimal. The outstanding EM wave absorption performance is attributed to the synergistic effect between dielectric and magnetic loss, good attenuation ability and excellent impedance matching. Moreover, covalent bonds considered to be carrier channels can facilitate electron migration, adjust EM parameters and then enhance EM wave absorption performance. This work provides a possible method for preparing efficient EM wave absorbers.