Novel MOF Lightweight Carbon-Based Composites Preparation And Eletromagnetic Wave Absorption Performance Study

In recent years,with the rapid development of communication technology,electromagnetic wave pollution problem is gradually being concerned.To solve the problem of electromagnetic wave pollution,research and development of efficient electromagnetic wave absorption materials（wave absorption materials）is of significant importance.Wave absorption materials are being actively searched to mitigate the pollution problems caused by electromagnetic waves.In this process,many characteristic wave absorption materials are widely used,such as magnetic metals/ferrites,conductive polymers,semiconductors,carbon materials and their related composites.Improving the impedance matching of the material and enhancing the electromagnetic wave attenuation capability effectively enhances the electromagnetic wave absorption performance.Metal organic framework（MOF）is an ideal precursor material that can be transformed into nanostructured functional materials by high temperature pyrolysis.MOF-derived carbon has a tunable structure,high porosity,light weight and chemical stability providing great advantages for the construction of excellent wave absorption materials.In this paper,four MOF-derived carbon composites with magnetoelectric synergy were prepared using MOF-derived porous carbon materials,and their phase composition,microstructure,electromagnetic parameters and wave absorption properties were investigated.The main research of this paper is as follows.（1）CoZn-ZIF was prepared by mechanical magnetic stirring,and CoZn/CNT composites with three-dimensional networks were synthesized by pyrolysis at high temperature.Due to the effective catalysis of melamine and the protection of N₂atmosphere,CoZn-ZIF was derived to form CoZn alloy and the N-doped CNT framework was densely grown on the surface of nanorods,which finally formed the three-dimensional network structure effectively.According to the results,the minimum value of reflection loss is-41.08 dB with an effective absorption bandwidth of 3.54GHz at a CoZn/CNT-25 wt.%with the thickness of 1.31 mm.the effective absorption bandwidth reaches 4.72 GHz at the thickness of 1.58 mm.（2）One-dimensional electromagnetic wave absorbers containing Coand CoFe alloy nanoparticles were prepared by electrostatic spinning,in situ growth and pyrolysis methods.The MOF was immobilized on the fiber surface using the pyrolysis method to obtain CF containing N with surface granularity.The results show that when the thickness of Co-CoFe@NC-800 is 2.67 mm,the optimal reflection loss value is-64.40dB and the effective absorption bandwidth is 3.94 GHz（1.56 mm）under the filling of40 wt.%.At a thickness of 4.17 mm and 50 wt%filling,Co-CoFe@NC-700 exhibits an optimal reflection loss value of-74.00 dB at low 7.66 GHz and an effective absorption bandwidth value of 5.16 GHz at the thickness of 2.42 mm.（3）Highly efficient electromagnetic wave absorption Ni Fe/Fe₃O₄/CF materials were prepared by electrostatic spinning technique,high temperature pyrolysis and surface modification.Fe-MOF was successfully grown on the fiber surface by surface chemical modification,and alloys,oxides and N-containing CF were generated by pyrolysis.Due to the magnetoelectric synergy effect of the composite material,the optimal reflection loss value is-67.14 dB（10.36 GHz）at a thickness of 3.1 mm,and the effective absorption bandwidth is 5.62 GHz（2.37 mm,11.68 GHz-17.3 GHz）.（4）The electromagnetic wave absorption FeCo/CNTs composites were successfully prepared by hydrothermal and pyrolysis techniques.The MOF-derived carbon and self-grown CNTs were successfully constructed as three-dimensional interconnected network structures.The three-dimensional network construction,synchronous double-loss mechanism and excellent impedance matching enabled the composites to exhibit excellent electromagnetic wave absorption performance.At the thickness of 1.38 mm,the minimum value of reflection loss could reach-59.21 dB.The widest effective absorption bandwidth is 4.92 GHz at a matched thickness of 1.6 mm,from 12.42 to 17.34 GHz.In summary,four MOF-derived carbon composites were successfully prepared in this paper,and their absorption properties were systematically investigated.The results show that the prepared composites all have excellent wave absorption properties and show good application prospects.This will point out the direction for the design of efficient and lightweight MOF-derived composite absorption materials in the future,and promote further research and development in this field.