Tris(4-ethynylphenyl) Amine-based Conjugated Microporous Polymers And Photocatalytic Water Splitting Hydrogen Evolution

At present,in order to solve the fossil fuel shortage and the related environmental pollution problem,the conversion of solar energy into hydrogen energy has become a hot issue.It is of great significance and value to explore new multifunctional monomer for design,construction and application of high-performance photocatalysts.Conjugated microporous polymers show potential application value in the field of hydrogen production by photocatalytic water decomposition due to the high photoabsorption rate,good stability,wide range of sources,low price,diverse synthesis methods,easy regulation of structure and energy level.In this paper,a series of conjugated microporous polymers were synthesized by connecting benzothiadiazole monomers using tri(4-acetylene phenyl)amine as synthetic unit.The main contents include:1.In order to develop novel multifunctional monomers and explore the influence of the connection position of polymerization units on the photocatalytic performance of polymers,four conjugated microporous polymers based on tri(4-acetylene phenyl)amine unit and benzothiadiazole unit were synthesized by sonogashira-Hagihara cross coupling reaction.The connection positions of benzothiadiazole units in the four polymers FS1,FS2,FS3 and FS4 were 5,6-position,4,5-position,4,6-position and 4,7-position,respectively.The morphology and properties of the polymers were analyzed by using Fourier transform infrared,UV-visible absorption,fluorescence analysis,powder X-ray diffraction,thermogravimetric analysis and BET test.It was found that the change of the connecting position of benzothiadiazole unit in the polymer can effectively regulate the properties of the polymer;under visible light illumination,the four polymers have obvious photocatalytic hydrogen evolution performance,among which the 4,7-position polymer FS4 has the best performance,and its hydrogen evolution efficiency is up to 115.74?mol g^-1 h^-1,nearly three times that of FS1.2.To develop novel high-performance multifunctional monomers and explore the effect of substituent effect on CMPs photocatalytic water decomposition,two kinds of three(4-acetylene phenyl)amine conjugated microporous polymers FS4 and FS5 were prepared by sonogashira-Hagihara coupling reaction.The effect of substituent effect on the properties of polymer materials was studied by analyzing the morphology,thermal stability,optical properties,porous properties and photocatalytic water decomposition under visible lightillumination.Research shows that:under visible light,the photocatalytic hydrogen evolution rates of FS4 without substitutions on benzothiadiazole unit and FS5 with methyl group on benzothiadiazole unit were115.74 and 100.61?mol g^-1 h^-1,respectively.Tris(4-acetynophenyl)amine CMPs have good photocatalytic water decomposition performance,tris(4-acetynophenyl)amine is a kind of CMPs multi-functional monomer with excellent performance.The presence of methyl group can regulate the conjugation level of the polymer and then adjust its bandwidth,but has little effect on the hydrogen evolution performance of the polymer.