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 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.

A Flexible and Lightweight Biomass-Reinforced Microwave Absorber

“…Hence, the superior microwave absorption capability of S2 should be attributed to the optimal combination of good impedance matching and adequately high attenuation capacity. Table 1 summarizes the EM absorption performance of some representative carbon-based magnetic absorbers in the recent literature [36,[47][48][49][50][51][52][53][54]. It is noteworthy that the strong microwave absorption of S2 at a low filler content of 20% is competitive to those reported EM absorbers.…”

Synthesis of Hierarchical Porous Carbon in Molten Salt and Its Application for Dye Adsorption

“…Figure 4 presents Raman spectra of porous carbon materials prepared at 800 °C for 2 h with various amounts of Fe. Two main peaks at 1350 and 1590 cm -1 were respectively assigned to the D band and G band [42]. With the increase of the Fe amount, the value of I D /I G increased initially and then decreased, demonstrating the existence of many defects in the as-prepared porous carbon.…”

Biomass-Derived Porous Carbon-Based Nanostructures for Microwave Absorption

“…5c). Wang et al [118] investigated the EM response (f) (e) (d) (g) 8 [118] behavior of diverse magnetic hierarchical porous carbon (MPC) composites prepared at different annealing temperature using loofah sponge biomass and Fe(NO 3 ) 3 ·9H 2 O as ingredients. From Fig.…”