Study On The Preparation And Electromagnetic Wave Absorption Performances Of MOFs-based Multi-hole Magnetic Metal Sulphides

With the rapid development of electronic information technology,electromagnetic(EM)wave absorption materials play a crucial role in national defense security,health care,electronic equipment and military stealth technology.Excellent EM wave absorption material can make weapon equipment play a key role on the battle field and can decide the success of battle field.At present,the traditional microwave absorbers own some defects(such as relatively high density),which restrict their widespread application.For the past years,the research of porous materials with hollow structures has become one of hotspots in the field of microwave absorption.This special framework has advanced microwave absorption performance.Microwave absorption materials reported so far also include materials derived from metal-organic frameworks(MOFs),which are characterized by their porosity and chemical diversity.Due to the shortcomings of traditional microwave absorption materials(high cost,large density,complicated preparation process,narrow effective absorption band),the design and preparation of high-performance microwave absorption materials derived from MOFs porous material with hollow porous morphology is an effective strategy.The research and development of the light weight,wide absorption band and high absorption strength of materials have become a hot research topic in the field of microwave absorption.Hollow Co S₂nanobubble prisms with hierarchical porous structure were successfully prepared through facile two-step self-engaged method to achieve high-performance EM wave absorption.By means of the characterization of BET,TEM and SEM,the specific surface area of the intermediate ZIF-67 is very high,which is due to the unique porous characteristics of MOFs.The ultimate product Co S₂forms a hierarchical porous hollow morphology.The hierarchical porous hollow morphology can reinforce the multiple reflections and scatterings.This is conductive to enhance the EM wave absorbing properties.In the experiment,the vector network analyzer is applied to measure the electromagnetic parameters of the samples,which could study the microwave absorbing properties of the samples.The measurement displays that the microwave absorbing properties of Co S₂-25wt%is relatively better within the scope of 2-18 GHz,compared with other sample filler loading of 15 wt%and 35 wt%.The minimum reflection loss of Co S₂-25 wt%at 5 GHz is-54.9 GHz with the preparation thickness of 4.5 mm.Effective absorption bandwidth(R_L<-10 d B)of Co S₂-25 wt%is 14.2 GHz(3.8-18 GHz).Moreover,by observing the electromagnetic parameters,it can be found that controlling the porous structure of cobalt sulfide will affect its microwave absorption performance.Hollow 10%Ni-Co S₂nanobubble prisms were fabricated by doping Ni element into precursor.Through the characterization of BET,TEM and SEM,it is found that 10%Ni-Co S₂retains all the morphology and structure characteristics of pure Co S₂.The polarization of the material system is regulated by doping Ni element,which could enhance the interface polarization and dipole polarization of the material surface.In the experiment,the vector network analyzer is applied to measure the electromagnetic parameters of the samples,which could study the microwave absorbing properties of the samples.The analysis displays that electromagnetic parameters and EM wave absorption properties of the 10%Ni-Co S₂can be adjusted by changing the sample filler loading.10%Ni-Co S₂-35 wt%displays the optimized microwave absorption properties,compared with other sample filler loading of 15 wt%and 25 wt%.The minimum reflection loss of 10%Ni-Co S₂-35 wt%at13.7 GHz is-47.7d B with the preparation thickness of only 1.68mm.The corresponding effective absorption bandwidth(R_L<-10 d B)is 3.5 GHz(12-15.5 GHz).