Ultra-light RGO/MnFe₂O₄/PI aerogel with oriented pore structure and ultra-broadband microwave absorption

Graphene aerogel, known for its excellent dielectric properties and porous structure, demonstrates outstanding electromagnetic wave absorption. In this study, we fabricated lightweight (11.16 mg/cm³) graphene composite aerogels incorporating reduced graphene oxide (RGO), manganese ferrite (MnFe₂O₄), and polyimide (PI) with oriented pore structures. The addition of MnFe₂O₄ enhances impedance matching and synergistically combines dielectric and magnetic loss mechanisms, significantly improving absorption performance. The composite exhibits an effective absorption bandwidth of 9.216 GHz, covering nearly the entire X and Ku bands (2–18 GHz), with a minimum reflection loss of −75.643 dB. In the 18–26.5 GHz range, the effective bandwidth reaches 7.80 GHz, with a minimum peak of −58.862 dB. At a thickness of 2–2.4 mm, the bandwidth extends to 8.5 GHz, covering the full 18–26.5 GHz range. With a thickness of 1.46–1.8 mm, the bandwidth reaches 13.5 GHz, spanning 26.5–40 GHz, and a minimum peak of −79.560 dB with an 11.30 GHz bandwidth. The oriented porous structure enhances electromagnetic loss, as confirmed through experimental and theoretical analysis. The composite also exhibits excellent mechanical strength and thermal insulation, attributed to its oriented microchannels. This work provides valuable insights for designing lightweight, broadband, and efficient graphene-based absorbers.