Biomass-derived HPCFs@Fe₃O₄microspheres and HPCFs@Fe₃O₄@HsGDY coated microspheres for electromagnetic wave absorption application

Herein, green synthesis of helical hierarchical porous carbon fibers (HPCFs) was carried through facile carbonization aided by low-cost hydrothermal carbonization (HTC) to fabricate HPCFs@Fe₃O₄ microspheres and hydrogen-substituted graphdiyne coated microspheres (HPCFs@Fe₃O₄@HsGDY) through Glaser coupling synthesis approach. HPCFs@Fe₃O₄ microspheres and HPCFs@Fe₃O₄@HsGDY coated microspheres are most competently used as electromagnetic wave absorber (EMWA) to eradicate deterioration caused by harmful electromagnetic waves (EMW) at a thin thickness. For instance, HPCFs@Fe₃O₄ microspheres at 30.0 % filling amount shown −49.91 dB reflection loss (RL) at 9.20 GHz with 2.70 mm and effective absorbing bandwidth (EAB, RL ≤ −10.00 dB) of 3.00 GHz (7.90–10.90 GHz). The EAB value was further improved to 5.40 GHz (12.00–17.40 GHz) at 1.90 mm. HPCFs@Fe₃O₄@HsGDY coated microspheres with 35.0 % filling amount exhibits wideband EAB of 4.50 GHz (9.00–13.50 GHz) with corresponding RL of −58.34 dB at 10.60 GHz over 3.20 mm. At 3.90 mm, the EAB value was further ameliorates to 6.10 GHz (7.70–13.80 GHz).