Study On Fabrication And Application Of Functional Composites Containing Cerium

As a semiconductor material,cerium oxide has a band gap of 3.15 e V.Due to excellent ultraviolet shielding performance,abundant oxygen vacancy,low refraction index,and low photocatalytic activity,it shows great application value in ultraviolet shielding and electromagnetic wave absorption.Superhydrophobic materials are widely used in self-cleaning,antifouling,anti-corrosion,oil-water separation,and other fields.Inspired by this,combined the superhydrophobic function with ultraviolet and microwave absorption in this thesis,a functional superhydrophobic composite containing cerium was prepared to explore its practical application in ultraviolet shielding materials and microwave absorption materials.In this thesis,cerium oxide/halloysite nanocomposite was prepared by in-situ growth method,and then modified by low surface energy reagent to prepare the composite with superhydrophobic UV shielding performance.The structure and composition of the material were analyzed by Scanning Electron Microscope(SEM),Transmission Electron Microscope(TEM),X-ray Diffraction(XRD),X-ray Photoelectron Spectroscopy(XPS),and Thermogravimetry(TG).Furthermore,by UV-vis absorption spectroscopy to characterize ultraviolet absorption performance of the material,and then the water contact angle of the composite material and self-cleaning ability are examined.Finally,the composite materials can effectively block the 98.7%and 86.0%of UVA,UVB,and achieved excellent superhydrophobic function with the water contact angle of 165~o at the same time,besides material self-cleaning ability has also been confirmed.Secondly,through one facile hydrothermal method,constructing the micro-nano structure of nanoparticles on the surface of graphene,cerium ferrite/graphene oxide composite material was prepared,through further hydrophobic treatment,the electromagnetic wave absorption composite with the superhydrophobic function was prepared.Afterward,the state of aggregation,composition,and structure features of material were analyzed by TEM,XRD,XPS,and the thermal stability of the material is measured by TG.The electromagnetic parameters of the material through a vector network are obtained.Ultimately,the hydrophobic property of materials with a water contact angle of 164~o is achieved,and the superhydrophobic material has a maximum reflection loss of-57 dB for microwave with an effective absorption bandwidth of 5.2 GHz,and on the condition of no loss of electromagnetic absorption capacity,which realized the superhydrophobic ability.Finally,through the introduction of the conductive network,cerium ferrite/carbon nanotube composite material was prepared by hydrothermal method,through the hydrophobic processing mechanism,functional superhydrophobic material with electromagnetic wave absorbing ability is successfully achieved.The state of aggregation and structure of the material is analyzed by TEM,XRD,XPS,the thermal stability of the material is measured through the TG,the water contact angle is also tested,through the calculation of electromagnetic parameters,we analyze the absorbing mechanism of absorbing materials.The result reveals that the dielectric loss of the prepared material mainly is complete through the conductivity loss of the conductive network.As expected that the composite material can absorb more than 90%electromagnetic wave in the range of 6.9 GHz,and the maximum absorption peak can reach-47 dB,and realize the superhydrophobic function.