Carbonized Design of Hierarchical Porous Carbon/Fe₃O₄@Fe Derived from Loofah Sponge to Achieve Tunable High-Performance Microwave Absorption

Abstract

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.