Abstract: Carbon-based electromagnetic wave (EMW) absorbing materials attached with metal sulfides famous for good dielectric properties are favored by researchers, which can form heterogeneous interfaces and thus provide supplementary loss mechanisms to make up for the deficiencies of a single material in energy attenuation. Here, Co₉S₈/Co@coral-like carbon nanofibers (CNFs)/porous carbon hybrids are successfully fabricated by hydrothermal and chemical vapor deposition. The samples have exceptional EMW absorbing properties, with a minimum reflection loss of -57.48 dB at a thickness of 2.94 mm and an effective absorption bandwidth of up to 6.10 GHz at only 2.20 mm. The interlocking structure formed by Co@coral-like CNFs, interfacial polarization generated by heterostructure of Co₉S₈, abundant defects and large specific surface area resulted from porous properties are important factors in attaining magnetic-dielectric balance and excellent absorption performance. Different matrixes are selected instead of paraffin to investigate the effect of matrix materials on EMW absorbing capacity. Besides, the EMW attenuation potential for practical applications is also demonstrated by radar cross-section simulations, electric field intensity distribution and power loss density. This work provides a novel strategy for designing outstanding EMW absorbers with unique microstructures using facile and low-cost synthetic routes.

Key words: Coral-like carbon nanofibers, Biomass porous carbon, Electromagnetic wave absorption, Co₉S₈, Magnetic-dielectric synergy