Application Of ZIFs Based Catalyst For Carbon Fixation By Photocatalysis And Oil-water Separation

The strategy of carbon neutrality and carbon peaking is an important measure to realize sustainable development,slow down the energy crisis and atmospheric warming.As the main source of energy developed on Earth is fossil fuels,their combustion leads to excessive emission of CO₂.In addition,excessive emission of CO₂ causes environmental problems such as global warming,ocean acidification,sea level rise and other impacts.To alleviate these problems,the search for sustainable,renewable and efficient methods to convert CO₂ directly into usable chemical fuels has received wide attention.Chemical fixation,catalysis,hydrogenation and other technologies have been used to convert CO₂ into a variety of available chemicals,among which solar energy,a stable and clean energy source,is a promising way to alleviate energy shortage and the greenhouse effect.However,the current photocatalysts still have some problems,such as low efficiency,high cost,instability and difficult recovery,which need further study.In this project,zeolite imidazole skeleton（ZIFs）is selected as the main material,3D sponge as the carrier,for photocatalytic CO₂ reduction and oil-water separation of multi-field applications.Mainly carried out the following work:（1）Study on the photocatalytic activity and stability of ZnO NFs/ZIFs under visible light.Three kinds of 3D ZIFs were loaded onto 1D ZnO NFs surface by in-situ growth method.Compared with a single sample,the specific surface area of the composite material is greatly improved.The microporous properties of ZIFs enable the composite sample to have a higher CO₂ adsorption capacity,which plays an auxiliary role in the photocatalytic CO₂ reduction reaction.UV-vis spectra show that the construction of heterojunction broadens the range of light response and improves the utilization of light energy.Electrochemical analysis shows that the composite samples have strong efficiency of electron separation and migration.Finally,XRD and TGA tests show the stability and thermal stability of different samples in water,showing excellent reusable performance of the samples.（2）Carbon fixation and oil-water separation performance of MS/PDA/Zn Co-ZIF-L/PDMS three-dimensional photocatalyst.Two-dimensional foliated ZIF-L nanosheets have randomly stacked slit pores,which enable light energy to be reflected several times and improve the utilization rate of light energy.Moreover,its unique cushion cavity makes it have excellent CO₂ adsorption capacity,which helps to improve photocatalytic performance.MS sponge as a carrier,its high porosity（99%）enables the sample to be fully in contact with CO₂,and can greatly improve the problems of insufficient contact with reactants and low light utilization efficiency caused by easy agglomeration of powder samples.In addition,the excellent mechanical properties of MS sponge greatly improve the sample recycling ability,greatly improve the powder material is not easy to recover,reuse ability is not strong defects.The wettability of the composite sponge was characterized by static contact Angle test,which showed that the composite sponge had excellent oil-water separation performance.（3）Carbon fixation and oil-water separation performance of CMS/g-C₃N₄/ZCZIF PDMS photocatalysis.The modified CMS sponges were obtained by treating MS sponges at different temperatures.Then ZCZIF nanoparticles were loaded on the surface of the sponges by in-situ deposition method,and then coated by PDMS,the composite functional sponges with the ability of photocatalytic CO₂ reduction and oil-water separation were prepared.The morphology,structure and composition were characterized by XRD,FTIR and SEM,and the band structure of each component was obtained by UV-vis and band gap energy estimation,combined with VB-XPS.The results show that the heterojunction construction provides an effective channel for rapid charge transfer in photochemical reactions.The black body effect of CMS brings about the improvement of the light capture ability of composite sponges and the photothermal effect,which is also one of the key factors for the improvement of photocatalytic efficiency.In addition,the wettability of the composite sponge was analyzed by the static contact Angle and the state of the sample in water,and the oil-water separation performance of the sample in different environments was discussed.