Pentagonal YbCoO₃-induced heterointerface engineering in rGO aerogels toward lightweight broadband microwave absorption and multifunctionality

Developing ultralight aerogels that simultaneously achieve efficient electromagnetic (EM) wave absorption and multifunctionality remains challenging because of the difficulty in synergistically regulating interfacial polarization, conductive networks, and hierarchical porous structures. In this work, an in-situ growth strategy is proposed to construct interface-rich YbCoO₃/reduced graphene oxide (rGO) aerogels, in which pentagonal YbCoO₃ units are grown in-situ and anchored within a three-dimensional (3D) rGO framework. This architecture enables precise tuning of the heterointerface density, conductive pathways, and porosity, thereby optimizing impedance matching and enhancing EM attenuation. Moreover, the introduction of Yb³⁺ ions with localized 4f electrons induces strong spin-orbit coupling and magnetic anisotropy, promoting high-frequency magnetic resonance and improving magnetic loss. Therefore, the optimized YbCoO₃/rGO aerogel (Ybr-3 sample) exhibits a remarkable minimum reflection loss (RL_min) of −62.4 dB at 3.2 mm and an ultrawide effective absorption bandwidth (EAB) of 10.0 GHz (8–18 GHz) at a thickness of 2.2 mm while maintaining an ultralow density of 0.0047 g/cm³ and a low filler content of 5 wt%. Additionally, a significant reduction in the radar cross-section (∼40 dB m²) confirms its superior EM wave attenuation capability. The hierarchical porous structure also imparts multifunctionality, including thermal insulation and efficient dye removal. Mechanistic studies reveal that the enhanced performance arises from the synergistic effects of interfacial polarization, conductive loss, magnetic resonance, and multiple scattering, which are further strengthened by 4f-3d electron interactions and interface-rich porosity. This work demonstrates that integrating in situ-growth-induced structural regulation with rare-earth electronic modulation provides an effective pathway for designing ultralight materials with broadband EM wave absorption and multifunctional properties.