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 Fe₃O₄@Fe nanoparticles. As expected, the as-obtained loofah sponge-derived 3D porous carbon/Fe₃O₄@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.

中文翻译：

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丝瓜络海绵衍生的分层多孔碳/ Fe ₃ O ₄ @Fe的碳化设计，以实现可调谐的高性能微波吸收

近来，源自生物质的三维（3D）多孔碳材料由于其低成本，广泛的可利用性和生物质的可持续性而作为有前途的微波吸收器而受到关注。本文中，提出了一种利用丝瓜海绵作为3D分层多孔碳前驱体和硝酸铁作为磁性前驱体来制备磁性分层多孔碳复合材料的新策略，该复合材料表现出可调的高性能微波吸收（MA）。在碳化过程中，丝瓜海绵的3D捆绑微管结构变为具有分层多孔结构的互连网络，并且硝酸铁前体转化为磁性Fe ₃ O ₄ @Fe纳米颗粒。不出所料，丝瓜海绵衍生的3D多孔碳/铁在600°C下处理的₃ O ₄ @Fe复合材料表现出出色的MA性能。厚度为2 mm时，它的最小反射损耗（RL）为-49.6 dB，有效吸收带宽（RL≤10 -dB）可以达到5.0 GHz（从13到18 GHz）。3D分层多孔结构，界面极化，介电损耗和磁损耗之间的协同增强，多次反射和散射使MA能力得到增强。我们的研究可能会提供一种有效且简便的策略来制备从生物质衍生的磁性多孔碳以用于MA应用。