Facile Fabrication of Co-Doped Porous Carbon Derived from Coal Hydrogasification Semicoke/ZIF-67 for High-Performance Microwave Absorption

A series of porous Co-doped porous carbon absorbers (SC/CoC) with favorable microwave absorption performance were synthesized originating from a coal hydrogasification semicoke (SC)/Zeolitic Imidazolate Framework (ZIF-67) precursor by a facile static reaction and subsequent pyrolysis approach. SC acts as an external carbon source to avoid structural instability and poor impedance matching characteristics inherent in ZIF-67. The influence of annealing temperature on the microstructure, graphitization degree, electromagnetic parameters, and the microwave absorption (MA) capabilities of SC/CoC composites was systematically investigated. The results demonstrated that the annealing temperature critically influenced the MA performance. When the absorber filling ratio is 30 wt %, the SC/CoC-800 composite exhibits the best MA performance with the minimum reflection loss (RL_min) of -40.89 dB at a thickness of 2.0 mm an effective absorption bandwidth of 4.58 GHz at 1.6 mm in thickness compared with its counterparts. The synergistic effects of conductive loss (porous carbon framework), magnetic loss (Co nanoparticles), polarization loss (dipoles and multiple heterointerfaces), and multiple scattering (pores) endowed the composites with favorable MA performances. This work not only proposes a scalable methodology for fabricating high-performance microwave absorbers but also establishes a sustainable approach to utilize industrial byproduct SC as value-added electromagnetic functional materials.