Engineering hierarchically porous and heterogeneous interfaces is a powerful strategy for obtaining high-performance microwave absorbers, because it simultaneously improves impedance matching and enhances polarization loss. However, the coordinated construction of both macro-/micro pore structures and a heterogeneous skeleton in a single-material system remains a significant challenge. Inspired by the intricate architecture of butterfly wings, the aerogels featuring aligned micro-channels and periodic nanoscale ridges were constructed from Gadolinium (Gd) and Bismuth (Bi)-based sub-1 nm nanowires via freeze casting. The coexistence of cellular pores and porous cell walls optimizes the impedance matching and promotes multiple scattering, while the internal nanodomain, comprising an amorphous phase alongside crystalline Gd₂MoO₆ and Bi, creates synergistic Schottky and amorphous/crystalline heterointerfaces. These interfaces enable substantial charge transfer and redistribution, thereby generating interfacial dipoles and intensifying Maxwell-Wagner polarization. Consequently, the-optimized aerogel exhibits a maximum effective absorption bandwidth of 8.3 GHz and a minimum reflection loss of −57.6 dB. This work pioneers the use of sub-1 nm nanowires as building blocks for the in situ construction of hierarchically porous aerogels with heterogeneous nanodomains, paving the way for advanced microwave absorption materials.

Heterogeneous interface engineering is key to tailoring intrinsic electromagnetic wave (EMW) attenuation. However, fully harnessing the functional benefits of these interfaces requires precise control of their architecture—a major challenge in hierarchical heterostructure design. Herein, a stepwise confinement strategy is proposed to construct hierarchical heterogeneous interfaces in situ within graphene aerogels, incorporating zeolitic imidazolate framework-67 (ZIF-67) nanoparticles and a polysilazane nanolayer embedding ZIF-67. Through synchronous thermal decomposition of magnetic metal and ceramics precursors, Co/CoO nanocrystals and an amorphous SiCN nanolayer are uniformly anchored onto the reduced graphene oxide (rGO) framework, creating hierarchically organized heterogeneous interfaces that comprise both nanoscale zero-dimensional (0D)–two-dimensional (2D) assemblies, such as ZIF-67-derived Co/CoO nanocrystals anchored on SiCN or rGO sheets, and extended 2D–2D contacts between the SiCN and rGO layers. These engineered heterointerfaces may induce an inhomogeneous spatial charge distribution, which in turn enhances interfacial polarization. Benefiting from synergistic magnetic–dielectric loss and improved impedance matching, the optimized magnetic graphene‒SiCN aerogel achieves a minimum reflection loss of −60.63 dB at a low frequency of 5.52 GHz and a broad effective absorption bandwidth of 7.89 GHz at a thickness of 2.4 mm. This work provides valuable insights into hierarchical heterostructure design and the fundamental electromagnetic response mechanisms governed by heterointerface engineering, paving the way for next-generation electromagnetic wave (EMW)-absorbing materials.