Interfacial engineering of flower-like Fe₃O₄@C/FRGO multiscale heterostructures for broadband and efficient microwave absorption

Rational microstructure design and compositional regulation have emerged as effective pathways to enhance electromagnetic wave (EMW) absorption, However, simultaneously achieving strong absorption, broad bandwidth, thin thickness and low filler loading remains challenging. Herein, three-dimensional hierarchical heterostructures comprising amorphous carbon-wrapped magnetite supported on flower-like reduced graphene oxide (Fe₃O₄@C/FRGO) was constructed through spray-drying assembly, spatially confined solvothermal crystallization, and defect-modulated carbonization. By tailoring the reduction degree of FRGO and tuning ferrite composition through thermal treatment, the dielectric-magnetic properties and interfacial interactions are precisely regulated. With merely ≈ 3.26 wt% incorporation of FRGO, the optimized composite exhibits a minimum reflection loss (RL min ) of -66.29 dB at 1.94 mm (20 wt% filler) and a broad effective absorption bandwidth (EAB) of 6.60 GHz (11.30–17.90 GHz) at 2.73 mm (30 wt% filler). This exceptional performance is attributed to the engineered heterointerfaces that facilitate multi-path energy dissipation via magneto–dielectric coupling optimized impedance matching, intensive interfacial polarization from abundant hierarchical architectures and the flower-like structure induced multiple scatterings. This study highlights the pivotal role of interfacial engineering in heterostructured absorbers and offers a design paradigm for high-performance EMW-absorbing materials through coordinated component–structure modulation. Graphical abstract The alternative text for this image may have been generated using AI.