Cobalt-doped silicon carbide/carbon aerogels via a polymer-derived strategy for ultraefficient microwave absorption

Abstract Silicon carbide/carbon (SiC/C) composites have shown great promise as high-temperature electromagnetic wave absorbers, yet their practical application remains limited due to inherent impedance mismatch. In this study, a polymer-derived strategy for synthesizing three-dimensional porous Co-doped SiC/C aerogels using silicon-arylacetylene resin (PSA) as the precursor was reported. The precursor solution was prepared via a thiol-yne click reaction combined with coordination between Co ions and alkyne groups, which was subsequently processed through ambient-pressure gelation, freeze-drying, and pyrolysis to obtain the final aerogel. Co enhances electrical conductivity and optimizes dielectric loss through lattice doping into intrinsic silicon vacancies (VSi), while simultaneously introducing additional magnetic loss via metallic Co nanoparticles generated by carbothermal reduction. Furthermore, Co catalyzes the in-situ growth of worm-like SiC nanowires, constructing multiple heterogeneous interfaces. This integrated modulation strategy effectively improved impedance matching and established a synergistic dielectric-magnetic loss mechanism. The optimized aerogel exhibited outstanding microwave absorption performance, achieving a minimum reflection loss (RLmin) of −61.51 dB at 13.10 GHz and an effective absorption bandwidth (EAB) of 4.70 GHz at an ultrathin thickness of 1.3 mm. This work provides an innovative route for developing transition-metal-doped porous materials and offers an effective strategy for designing high-performance electromagnetic wave absorbers with tailored properties.