EMI shielding properties of graphene-decorated magnetic oxide nanoparticle-reinforced carbon composite foams: A comparative study of graphene@NiO, graphene@Co₃O₄, and graphene@Fe₃O₄ fillers

The rapid development of electronics and instrumentation in recent years has raised increasing concerns about electromagnetic interference (EMI). To address this issue, the present study investigates the potential of carbon foam for EMI shielding applications. The aim is to enhance the EMI shielding effectiveness of carbon foam by integrating three distinct types of magnetic oxide (MO) nanoparticles (NPs). Graphene-incorporated carbon foam (Gr@CF) was primarily synthesized by impregnating phenolic resin and 2 wt% of graphene into polyurethane (PU) foam, then stabilization and carbonization at 1000°C in a nitrogen atmosphere. To further enhance the EMI shielding properties of the carbon foam, graphene-decorated MO-NPs (Gr@MO-NPs), specifically NiO, Co₃O₄, and Fe₃O₄, were individually incorporated. The addition of these Gr@MO-NPs resulted in a significant improvement in the EMI shielding performance. Among the various combinations tested, the carbon foam reinforced with graphene-decorated Fe₃O₄ NPs (Gr@Fe₃O₄-CF) exhibited an outstanding total EMI shielding effectiveness (SE T ) of 86.6 dB, a high absorption efficiency (SE A ) of 83.1 dB, and a low reflection efficiency (SE R ) of 3.5 dB. The remarkable EMI shielding absorption was attributed to the increased number of interfaces, defects, and dipole polarization within the foam, which facilitated the absorption and scattering of electromagnetic waves, enhancing the overall shielding performance. • Synthesis of carbon foams reinforced with graphene-decorated magnetic oxide nanoparticles, specifically NiO, Co₃O₄ and Fe₃O₄. • The resulting foams exhibited notable improvements in compressive strength, thermal stability, and EMI shielding properties. • Among them, the Gr@Fe₃O₄-CF achieved an SET of 86.6 dB, primarily attributed to the SE A of 83.1 dB and SE R of 3.5 dB. • These foams show strong potential for use as radar-absorbing materials, particularly in stealth and defense technologies.