Pearl necklace-like CoMn-based nanostructures derived from metal-organic frames for enhanced electromagnetic wave absorption

Abstract

Metal-organic frames derived magnetic nanostructures have potential applications in various fields. However, the magnetic particles in the derivatives are frequently agglomerated, limiting their physicochemical properties. Herein, we cross CoZn-MOF particles through ultra-long MnO2 nanowires (MnO2@CoZn-MOF) as precursor for high-performance functional materials. After the carbonization of the MnO2@CoZn-MOF, MnO2 nanowires were transformed into MnO nanowires coated with N-doped carbon layer (MnO@CN), while the CoZn-MOFs were converted into N-doped carbon polyhedron particles encapsulated with Mn3Co7 alloy nanoparticles (Mn3Co7@CN), leading to the formation of hierarchically pearl necklace-like nanostructure (CoMn@CN). The magnetic Mn3Co7@CN nanoparticles are separated uniformly along one-dimensional MnO@CN nanowires, and thus the self-agglomeration of magnetic nanoparticles is avoided efficiently. As a result, the CoMn@CN exhibits excellent electromagnetic wave absorption property with an effective absorption bandwidth of 5.24 GHz as the matching thickness is only 2.0 mm. Experimental results and theory calculations indicate that the improved conductive loss and dielectric relaxation loss caused by abundant heterointerfaces and the electronic interaction between Co and Mn atoms are responsible for the excellent electromagnetic wave absorption performance. Our strategy provides an efficient way for the synthesis of high-performance MOFs-derived nanostructures.