Co/CeO₂/C composites derived from bimetallic metal-organic frameworks for efficient microwave absorption

CeO₂, an n-type semiconductor material, has been widely used in microwave absorption (MA) due to its unique structural features such as oxygen vacancies and interstitial atoms. In this paper, Co/CeO₂/C composites were prepared by a hydrothermal method followed by a pyrolysis process. The effect of different pyrolysis temperatures (650-950 °C) on the MA property of the composites was investigated. When the pyrolysis temperature was 850 °C, the Co/CeO₂/C-850 composite exhibited outstanding MA behavior in the frequency range of 2-18 GHz, displaying a minimum reflection loss (RL_min) of -45.22 dB and an effective absorption bandwidth (EAB) of 4.61 GHz at a thin thickness of 1.75 mm. The MA performance of the Co/CeO₂/C composites is mainly attributed to the dielectric loss due to interfacial polarization originating from different interfaces and dipole polarization caused by the oxygen vacancies in CeO₂. In addition, the introduction of Co nanoparticles not only provides the magnetic loss but also modulates impendence matching for the current magnetoelectric coupling system.