Hierarchical carbonaceous composites with dispersed Co species prepared using the inherent nanostructural platform of biomass for enhanced microwave absorption

Task-specific carbonaceous composites which can inherently inherit the nanostructures of biomass precursors have aroused great attention due to the characteristics of unique macro-/microporous structures, vastly available and renewability. Herein, aiming for efficient microwave absorption, hierarchical porous C/Co composites were prepared by simple dipping and carbonization process using agarics as hierarchical framework platform for magnetic Co species. The role of Co nanoparticles, Co loading amounts and carbonization temperature were systematically investigated by establishing the relationship between structural characteristics and microwave absorption performance. The prepared samples displayed enhanced microwave absorption performance than the pure carbon derived from agarics; it could mainly attribute to the synergistic effect between graphite carbon and Co nanoparticles. When the filling rate was 30%, the HPC/Co-800 showed the best EM wave absorption performance. The minimum RL was -52.62 dB at 8.56 GHz in 2.8 mm. The widest absorption bandwidth reached 5.44 GHz when the RL was -49.63 dB at only 1.9 mm. This work may pave a new avenue to develop sustainable high effective absorber by recyclable biomass materials.