Optimizing impedance matching by a dual-carbon Co-regulation strategy of Co₃O₄@rGO/celery stalks derived carbon composites for excellent microwave absorption

Both macroscopic composition and microstructure should be considered for reasonable microwave absorbent designing. In this study, Co₃O₄@reduced graphene oxide (rGO)/Celery stalks derived carbon (CDC) was prepared by loading Co₃O₄ particles into rGO and biomass-derived carbon mixture through oxidation precipitation. By changing the mass ratio of rGO to CDC, the dielectric and impedance matching properties of the composites can be easily regulated. The RL_min value of Co₃O₄@rGO/CDC₁₃ composite (weight ratio for rGO:CDC is 1:3) reaches –84.3 dB with a thickness of 4.6 mm, and the widest effective bandwidth can be obtained at 4.5 GHz with a matching thickness of 2.8 mm. The Co₃O₄@rGO/CDC₁₃ composite with multiple components (Co₃O₄, CDC, rGO) and 3D net structure produces magnetic/dielectric loss combinations, interfacial polarization, and multiple reflections and scattering, and the CDC with half tube and half sheet structure is conducive to the optimization of impedance matching. The strategy of co-regulating dielectric properties of materials with double carbon provides a novel pathway for the preparation of lightweight, low-cost, and high-performance absorbers.