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[Display omitted] • Coral-like Co@CoO/RGO nanohybrids with crosslinked structure have been successfully fabricated. • The crosslinked structure builds abundant heterointerfaces and conductive network. • Yielding good electromagnetic wave absorption performance via the synergy of dielectric loss and magnetic loss. • The absorption reaches to −64.67 dB and effective bandwidth covers the whole X band at a thickness of 2.53 mm. The combination of magnetic and dielectric materials followed by appropriate structure design is an effective approach to achieve high electromagnetic wave absorption properties. Here, crosslinked Co@CoO/reduced graphene oxide nanohybrids (CCRGO) were fabricated via a simple three-step method. The experimental results show that compared with previous works, the as-prepared CCRGO nanohybrids achieve higher electromagnetic wave absorption and broader effective bandwidth at a lower filler loading. The electromagnetic parameters and electromagnetic wave absorption performance could be apparently adjusted by controlling the adding content of graphene oxide (GO) and the reduction temperature. Among a series of samples, CCRGO3-650 nanohybrid yields the best electromagnetic wave absorption performance benefiting from the proper GO addition and reduction temperature. At a filler loading of 20 wt%, the maximal reflection loss reaches to −64.67 dB at a thickness of 2.53 mm and the effective bandwidth below −10 dB covers the whole X band at a thickness of 2.51 mm. The good performance may be ascribed to the advantages of the dielectric and magnetic component as well as the special crosslinked structure, which triggers a synergistic absorption mechanism including multiple reflection/scattering, interface polarization, dipole polarization, conductive loss, eddy current loss, exchange resonance in the electromagnetic wave dissipation process. The good electromagnetic wave absorption performance affirms the potential application of CCRGO nanohybrids in the field of stealth materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous Fe/FeO/Fe 2 O 3 nanorods anchored on RGO form crosslinked FFORGO composite. • Coupling high loss and impedance match by adjusting dielectric and magnetic components. • Achieving multiple absorption mechanism and good EM wave absorption property. Electromagnetic wave absorbers composed of reduced graphene oxide (RGO) and magnetic nanoparticles integrates dielectric and magnetic loss features, which is extremely desirable for enhancing electromagnetic wave absorption ability. Here, porous Fe/FeO/Fe 2 O 3 nanorods/RGO composites (FFORGO) are synthesized via anchoring FeO(OH) nanorods on graphene oxide (GO) through dopamine polymerization followed by thermal reduction treatment. The porous Fe/FeO/Fe 2 O 3 nanorods are anchored on RGO, and crosslinked structure formed in FFORGO composites when the GO addition is higher than 5 mg‧ml−1. The abundant active sites (e.g., functional groups, dangling bonds, and lattice defects), the numerous heterointerfaces (among Fe, FeO, Fe 2 O 3 and RGO) and crosslinked structure trigger multiple dipole polarization, interface polarization and enhanced conductive loss. The EM wave absorption property is optimized by tuning the GO addition. FORGO4 with filler loading of 30 wt% achieves the maximal reflection loss of −24.1 dB at a thickness of 1.9 mm and the effective bandwidth below −10 dB of 3.01 GHz with a thickness of 2.2 mm, owing to the proper ratio of Fe/FeO/Fe 2 O 3 nanorods/RGO and synergistic effect between dielectric loss (dipole polarization, interface polarization, conductive loss) and magnetic loss (eddy current loss and exchange resonance). With the filler loading of 35 wt%, the maximal reflection loss of FFORGO4 is −50.7 dB at a thickness of 1.7 mm and the effective bandwidth reaches to 3.74 GHz at a thickness of 1.8 mm. [ABSTRACT FROM AUTHOR]