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Making full use of the interface modulation-induced interface polarization is an effective strategy to achieve excellent microwave absorption (MA). In this study, we develop an interfacial modulation strategy for achieving this goal in the commonly reported dielectric carbon nanotubes@polyaniline (CNTs@PANi) hybrid microwave absorber by optimizing the CNT nanocore structure. The heterogeneous interfaces from PANi and CNTs can be well regulated by longitudinal unzipping of the walls of CNTs to form 1D CNT- and 3D CNT-bridged graphene nanoribbons and 2D graphene nanoribbons. By controlling the oxidation peeling degree of CNTs, their interface area and defects are enhanced, thus producing more polarization centers to generate interfacial polarization and polarization relaxation, and also introducing more PANi loadings. Furthermore, more interface contact area can be produced between CNTs and PANi. This could induce a strong dielectric resonant and further improve the impedance matching, leading to significant enhancement of MA performance. With filler loading of only 10 wt % and a thinner coating thickness of 2.4 mm, the optimized CNTs@PANi exhibits excellent MA performance with the minimum reflection loss (RLmin) value of −45.7 dB at 12.0 GHz and the effective bandwidth is from 10.2 to 14.8 GHz. Meanwhile, the broadest effective bandwidth reaches 5.6 GHz, covering the range of 12.4–18.0 GHz with a thin thickness of 2.0 mm and its RLmin reaches −29.0 dB at 14.6 GHz. It is believed that the proposed interfacial modulation strategy can provide new opportunities for designing efficient MA absorbers.

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Recently, three-dimensional (3D) porous carbon materials derived from biomass have been gaining interest as promising microwave absorbers due to their low cost, vast availability, and sustainability of biomasses. Herein, a novel strategy of utilizing loofah sponge as 3D hierarchical porous carbon precursors and ferric nitrate as magnetic precursor to prepare magnetic hierarchical porous carbon composites, which exhibit tunable high-performance microwave absorption (MA). During the carbonization process, the 3D-bundled microtube structure of loofah sponge changes into interconnected networks with hierarchical porous structures, and the precursor ferric nitrate converts into magnetic Fe 3 O 4 @Fe nanoparticles. As expected, the as-obtained loofah spongederived 3D porous carbon/Fe 3 O 4 @Fe composites treated at 600 °C exhibit outstanding MA performance. It displays the minimum reflection loss (RL) of −49.6 dB with a thickness of 2 mm, and the effective absorption bandwidth (RL≤ 10 -dB) can reach 5.0 GHz (from 13 to 18 GHz). The 3D hierarchical porous structures, interfacial polarization, synergistic enhancement between dielectic loss and magnetic loss, multiple reflections, and scatterings make enhancement to the MA capability. Our research might provide an effective and facile strategy to prepare magnetic porous carbon derived from biomass for MA applications.

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