Synergetic Dielectric and Magnetic Losses of a Core–Shell Co/MnO/C Nanocomplex toward Highly Efficient Microwave Absorption

High-performance microwave-absorbing materials (MAMs) derived from metal–organic frameworks (MOFs) have attracted considerable attention due to their tunable chemical composition and microstructure. In this contribution, a core–shell-structured Co/MnO/C nanocomplex was prepared using a CoMn-MIL MOF by a facile hydrothermal synthesis and subsequent pyrolysis process. The optimal microwave absorption (MA) property of the as-prepared Co/MnO/C nanocomplex was achieved by the regulation of the Co2+/Mn2+ molar ratio. The minimum reflection loss (RLmin) of the Co/MnO/C-31 nanocomplex was low to −55.0 dB at 16.2 GHz with a thickness of 1.49 mm, and the effective absorption bandwidth (EAB) was high to 5.95 GHz (12.05–18 GHz) at a thickness of 1.8 mm. The mixed-metal nanocomplex with the core–shell structure exhibited outstanding MA performance, corresponding to the synergetic effect of the magnetic and dielectric loss. It provides a high efficiency strategy for rendering low reflection loss and broad EAB to high-performance MAMs.