Hierarchical porous carbon frameworks derived from Juncus effusus biomass with robust electromagnetic wave absorption properties

Biomass-based carbon materials exhibit remarkable potential for electromagnetic wave (EMW) pollution protection due to their extremely low density, inconceivable structure, and exceptional dielectric loss properties. In this study, a biomass-derived electromagnetic absorber (EMA) was developed using Juncus effusus (JE), and the 3D hierarchical porous framework was well maintained during a simple carbonization process, achieving a reflection loss (RL) value of -40.4 dB and a broad effective absorption bandwidth (EAB) of 3.48 GHz for JE-700 at the thickness of merely 1.75 mm. Besides, the maximum radar cross-section (RCS) reduction value of 32.4 dB m(2 )was achieved at an incident angle of 0 degrees. The synergistic effects of multiple loss mechanisms for the JE-derived EMA include conduction loss arising from the carbonized skeleton, multi-reflection of EMWs in regularly arranged micro-triangle units and hollow skeletons, and the numerous interfacial polarizations associated with boundary-type defects present in the amorphous and graphite phase carbon, as well as between the microelements (P, K, and Si) and carbon atoms. Therefore, the inherent 3D hierarchical porous framework offers novel inspirations and insights for designing biomass-derived EMAs.