Preparation and performance of porous carbon microwave absorber with high porosity from carbonized natural plant fibers

Herein, we present a novel fabrication approach to synthesize lightweight, highly porous, high-frequency microwave absorbers via temperature-induced manufacturing of 1D helical/chiral porous carbon fibers (HPCFs). This approach is unmatched in its effectiveness. Furthermore, this unique fabrication approach does not require pre-treatments such as activation, complex stripping-off processes, or harmful chemicals to generate the microwave absorber (MA). The MA with nanoscale/microscale structures, multidimensional 0 or 1D integration, helical/chiral configuration, and assorted loss mechanisms endow the absorber with exemplary microwave absorption capabilities. The maximum reflection loss (RL_max) of HPCFs-700–22.5 % (700 and 22.5 % correspond to the temperature at which biomass fiber get carbonized and the amount of filler material present) achieves −57.40 dB RL_max at 15.20 GHz with the wide effective absorbing bandwidth (EAB, RL_max ≤ −10 dB) of 5.40 GHz (12.60–18.00 GHz) and 2.47 mm thickness. Notably, at a matching thickness of 2.60 mm, the EAB improved to cover 12.00–18.00 GHz (6.00 GHz). Moreover, HPCFs-800–22.5 exhibit ultrawide EAB covers of 14.60–18.00 GHz (3.40 GHz), while RL_max surpasses −57.80 dB at the matching thickness of 1.51 mm. HPCFs-900–22.5 % achieve RL_max of just −51.00 dB with EAB of 5.40 GHz (12.60–18.00 GHz) at 14.90 GHz, while the matching thickness of absorber is 2.22 mm. The HPCFs with such exceptional microwave absorption properties shed light on the development economical and environmentally friendly MA with comparable microwave performances over exceptional EAB.