GO@CNT@Fe₃O₄@CuO quaternary nanohybrids enhance dielectric-magnetic synergy for high-performance epoxy-based electromagnetic absorbers

This study introduces a novel quaternary GO@CNT@Fe₃O₄@CuO core-shell nanohybrid designed to overcome impedance mismatch limitations in electromagnetic (EM) absorbers. Through stepwise synthesis, we integrated dielectric (GO, CNT), magnetic (Fe₃O₄), and semiconducting (CuO) components to create synergistic loss mechanisms. When incorporated at only 5 wt% into epoxy resin, the nanocomposite achieved exceptional X-band absorption with a minimum reflection loss of - 37.5 dB at 10.25 GHz and an effective absorption bandwidth of 3.2 GHz (9.0-12.2 GHz) at 5.0 mm thickness. The enhanced performance stems from balanced complex permittivity (ε' = 6.1, ε″ = 2.6) and permeability (µ' = 1.28, µ″ = 0.19), enabling optimal impedance matching and multi-mechanism attenuation through conduction loss, interfacial polarization, and magnetic resonance. This work establishes a design principle for low-loading, high-efficiency EM absorbers suitable for 5G and aerospace applications.