Morphological Modulation And Electronmagnetic Wave Absorption Properties Of Mof-Derive Metal/Carbon-Based Magnetoelectric Composites

The synthesis of new electromagnetic wave absorption materials are of great significance in modern national defense and electronic information technology.Due to the designability of metal organic framework materials（MOFs）in terms of structure,properties,and morphology,they show unique advantages as precursors in the construction of high-performance electromagnetic wave absorbing materials with specific composition,structure and morphology.In this thesis,based on the structural design,MOFs were compounded with Mn O₂,Mo S₂ and Ni Fe₂O₄ respectively,then subjected to high-temperature calcination to obtain a series of magnetoelectric coupled composites with specific composition and morphology,and the electromagnetic wave absorption properties of the composites were investigated.The main studies are as follows.Firstly,the bimetallic Co Zn-MOF was grown orderly on the surface of Mn O₂ by in-situ synthesis method to obtain Mn O₂@Co Zn-MOF and then subjected to high-temperature calcination to obtain a series of composite wave-absorbing materials Mn O@Co Zn/C with three-dimensional net-like structure.By changing the amount of Mn O₂,the morphology of the three-dimensional net-like Mn O@Co Zn/C composites was controlled,so as to optimize the absorbing properties of the system through the synergistic effect of components and structure.Control the amount of Mn O₂,the obtained composite MZC-2 had better electromagnetic wave absorption performance.The best reflection loss value was-27.54 d B at 15.76 GHz with the thickness of 1.5mm and corresponding effective absorption bandwidth was 4.40 GHz.Secondly,the bimetallic Co Ni-MOF was treated at high temperature to obtain Co Ni/C composite with rhombic dodecahedral morphology.Then using hydrothermal method combined with primary growth method,the flower-like composite absorbing material Co Ni/C@Mo S₂ was obtained by growing Mo S₂ nanosheets on the surface of Co Ni/C.The shell thickness of Co Ni/C@Mo S₂ was regulated by changing the content of Mo S₂,thus the synergistic effect of components and structure could be fully exploited to optimize the absorbing performance of the system.Control the amount of Mo S₂,the obtained composite CNM-2 had better electromagnetic wave absorption performance.The reflection loss value was-33.36 d B at 5.12 GHz with the thickness of 5.0 mm and the effective absorption bandwidth was 4.64 GHz at the thickness of 2.0mm.Finally,Ni Fe₂O₄ with different morphologies were synthesized by hydrothermal method and then their surfaces were coated with ZIF-67 to obtain Ni Fe₂O₄@ZIF-67precursors.Subsequently,the precursors were calcined at high temperature to successfully construct Ni Fe₂O₄/Co C_x/C composite absorbing materials with different morphology.Among them,the nanosphere-like N-Ni Fe₂O₄/Co C_x/C composite had the best performance.The reflection loss value was-55.05 d B at 10.24 GHz with the thickness of 2.0 mm,and the widest effective absorption bandwidth was 3.20 GHz at the thickness of 1.5 mm.