The Construction And Catalytic Performance Of Perylene Diimide Based Photocatalyst

Due to the increasingly serious problems of energy exhaustion and environmental pollution caused by over-exploitation and utilization of fossil energy,it is urgent to develop a new sustainable energy conversion system.Among them,photocatalysis technology is one of the green technologies with important application prospects in the field of energy and environment.Applications of photocatalysis include photohydrolytic hydrogen production with reduction reaction as the main reaction,pollutant degradation with oxidation reaction as the main reaction,and selective oxidation of organic compounds.Perylene diimide,as a novel photocatalyst,attracted a lot of research interest due to its adjustable structure,excellent electronic and optical properties,high extinction coefficient and low cost.However,in the actual reaction process,low charge separation efficiency and reducing capacity limited the photocatalytic activity of perylene diimide,so it became the key of the current research to explore appropriate optimization methods to improve the activity of perylene imide photocatalytic materials.In this thesis,perylene imide photocatalytic materials as the main research object,through the study of group modification,morphology and active site regulation,heterogeneous structure construction,self-assembly strategy and other modification methods to enhance the photoabsorption range of the catalyst,photogenerated carrier separation and migration,and surface catalytic reaction processes.The prepared catalyst was applied to photocatalytic hydrogen production and photocatalytic aerobic oxidation reactions.The detailed research content is as follows:1.Organic semiconductor PDIIM was synthesized by modifying PDI（perylene diimide）through amide condensation reaction with 1-（3-aminopropyl）imidazole.Then,using organic material PDIIM as template,the three-dimensional heterojunction ZIS/PDIIM photocatalysts were prepared by hydrothermal in situ self-assembly synthesis with sulfur indium zinc（ZIS:Zn In₂S₄）.The results show that the introduction of organic template PDIIM regulates the morphology and growth rate of Zn In₂S₄nanocrystals,resulting in the appearance of ultra-thin nanocrystals and the generation of S defects.Moreover,the construction of heterostructures not only broadens the intrinsic light absorption range of Zn In₂S₄,but also enhances its charge separation ability.In addition,due to theπ-conjugated aromatic ring structure of PDIIM,the catalyst ZIS/PDIIM has good photothermal effect and high spectral utilization efficiency,which synergistically promotes the improvement of photocatalytic hydrogen production activity.ZIS/PDIIM showed the best photocatalytic hydrogen evolution rate（13.04 mmol/g/h）under ultraviolet-visible light irradiation,which was 2.64 times and14.02 times of the original ZIS（4.93 mmol/g/h）and PDIIM（0.93 mmol/g/h）,respectively.The enhancement of activity and reaction mechanism were further studied by a series of characterization methods.It is worth noting that in the research work of this system,the multi-effect integration strategy of heterojunction effect,morphology regulation and photothermal effect is used to provide a unique perspective for the construction of efficient solar photocatalyst hydrogen evolution.2.In addition to exploring the carrier effect and photothermal effect of perylene imide materials in the system to enhance the photocatalytic hydrogen evolution performance of inorganic materials,this paper also explored further the catalytic oxidation performance of perylene imide materials by giving full play to the advantages of their energy band structure,and achieved excellent results in the photocatalytic selective aerobic sulfide oxide.Specifically,System 2 synthesized a series of perylene imide photocatalysts（P-PDIN,P-PDIC,P-PDIP）by using a series of functional group modification and self-assembly strategy,and revealed the structure-activity relationship between perylene imide materials modified by different groups and their photocatalyst activities.Further DFT calculation and electrochemical tests showed that the dipole moment of perylene imide modified by groups with greater electronegativity was larger,which was beneficial to enhance the internal electric field of the catalyst.In addition,the supramolecular system constructed by the self-assembly strategy can effectively improve the separation of photogenerative carriers and provide a convenient and efficient channel for charge transport.In summary,as a metal-free photocatalyst without any sacrificial agents or other co-catalysts,the catalytic system shows excellent conversion and selectivity for sulfone formation from sulfide,which can reach 99.94%and 99.76%,respectively.The study of system 2 showed that the catalytic performance of perylene imide photocatalyst was optimized from the perspective of group modification and self-assembly,which provided a good reference for the development of efficient catalyst preparation of selective aerobic sulfide oxide for photocatalysis.