| Organic polymer photocatalysts have the advantages of diverse synthesis methods,easy structure design,and easy control of physical and chemical properties,which have great potential in the field of photocatalytic water splitting hydrogen production,and have received extensive research attention in recent years.However,most of the reported organic polymer photocatalysts have a wide band structure and weak absorption of visible light,resulting in low visible light hydrogen production activity.Therefore,how to broaden the visible light absorption range of organic polymer photocatalysts and improve the carrier transmission and separation performance through reasonable molecular design is of great significance to constructing high-efficiency organic polymer photocatalysts.This master's thesis designed and synthesized a series of organic polymer photocatalysts with core-shell structure,D-?-A and D-A structure by adjusting and optimizing the molecular structure of organic conjugated polymers,and systematically studied the chemistry of polymers and the effect of structure,electronic properties and comonomer ratio on the performance of photocatalytic hydrogen production.A high-efficiency organic polymer photocatalyst with a photocatalytic hydrogen production rate of 105.1 mmol h-1 g-1 was obtained.The main research contents of this thesis are as follows:(1)Based on the idea that the core-shell structure can more fully expose the active sites,we synthesized an organic polymer photocatalyst of core-shell structure with pyrene as the core and dibenzothiophene sulfone as the shell by controlling the comonomer feeding sequence.,and investigated the influence of the ratio of comonomers on the performance of photocatalytic hydrogen production.The results show that the relative content of pyrene in the inner core and dibenzothiophene sulfone in the outer shell has an important influence on the photocatalytic hydrogen production performance.When the molar ratio of pyrene to dibenzothiophene sulfone is 50:50,the prepared polymer C-S-3 has the highest photocatalytic hydrogen production activity of 4.9 mmol h-1 g-1 under ultraviolet-visible light irradiation.(2)Using the ternary statistical copolymerization method,a series of D-?-A co-polymer photocatalysts with different chemical compositions and structures were designed and synthesized by adjusting the relative content of the electron donor unit(D)and the electron acceptor unit(A).It has been shown that the D-?-A molecular structure improved the coplanarity of the polymer,which is conducive to the rapid transmission of photogenerated carriers.Meanwhile,the variety of relative content of electron donor units and electron acceptor units lead to changes in the number of active sites and changes in the polymer microstructure,which has an important impact on the photocatalytic hydrogen production activity.When the molar ratio of electron donor to acceptor is 25:75,the prepared polymer PyBS-3 has stronger visible light absorption capacity and more photocatalytic active sites.The photocatalytic hydrogen production rate of PyBS-3 is 105.1 mmol h-1 g-1 under ultraviolet-visible light irradiation and exhibit a highest external apparent quantum yield of 29.3%at 420 nm.(3)Using the direct C-H aryl coupling polymerization reaction,the D-A type organic conjugated polymer photocatalyst containing bissulfone group was designed and synthesized,and the influence of the polymer's topological structure on its photocatalytic hydrogen production performance was studied.The results show that the introduction of bissulfone groups can improve the separation photogenerated electrons and holes.Compared with the one-dimensional linear polymer 2PyBDTO,the polymer 4PyBDTO with a three-dimensional cross-linked structure has a wider light absorption spectrum,a higher degree of conjugation and more photocatalytic active sites,thus showing a higher photocatalytic hydrogen production activity of 34.9 mmol h-1 g-1 under ultraviolet-visible light irradiation. |
PDF Full Text Request