Electromagnetic wave absorption performance of Fe3O4/activated carbon-natural resin nanocomposite

• A novel Fe3O4/resin nanocomposite (FEOR) achieved an outstanding reflection loss of −71.09 dB at a thickness of only 1 mm. • The FEOR sample exhibited near-ideal impedance matching (close to 1), leading to high absorption performance. • The use of biomaterials (oleaster seeds and apricot tree gum) provides a sustainable approach to developing high-efficiency microwave absorbers. • The presence of defects and porous structures enhances microwave attenuation through dipole polarization and charge carrier trapping.