Synthesis of MOF-derived porous multi-metal/carbon composites by metal regulation strategy for efficient microwave absorption application

The combination of carbon and ferrimagnet metallic materials derived from metal-organic frameworks (MOFs) have received increasing research interest for high performance electromagnetic wave absorption (EMA) materials due to their unique composition and microstructure. Here, a series of MOF-74 is synthesized by tuning the ratio of mixed metallic ions of cobalt and nickel, which are then treated in an inert atmosphere to fabricate novel composites with metallic cores encapsulated in a porous carbon shell. The dielectric loss caused by carbon shells and the magnetic loss caused by the cores of cobalt, nickel, or their alloys, coupled with the interfacial polarization caused by the space charge formed between the magnetic cores and the dielectric carbon shells, the highly efficient electromagnetic wave absorption performance of the composites is ensured. Ni@PC has a better EMA with an effective absorption bandwidth of 4.72 GHz at a thickness of 2.66 mm, while CoNi@PC_1 has an effective absorption bandwidth of 4.16 GHz at a thickness of 2.08 mm and is the thinnest at similar absorption widths. The properties obtained in this study indicate that the bimetallic MOF-74 with adjustable metal-ion ratio provides a new idea for the fabrication of high-efficiency MOF-based EMA materials.