| At present,increasingly prominent environmental pollution problems threaten the ecosystem on which we humans depend.Among them,the water environment,as the source of life for all things,is also facing serious problems such as organic pollution.How to develop and use clean solar energy to solve this kind of environmental problems has become one of the eagerly concerned topics of researchers.Semiconductor technology has regarded as one of the most promising methods for solving such environmental problems due to its advantages of high efficiency,low energy consumption and no secondary pollution.After years of development,organic semiconductor materials have received more and more attention.Compared with inorganic semiconductors,organic semiconductors have many incomparable advantages,including more readily available raw materials,lower costs,more controllable structures,wider light response ranges,and easier synthesis options.All of these have made organic semiconductors a research hotspot in the field of photocatalysis in the past few decades.As a typical n-type semiconductor material,perylene imide（PDI）and its derivatives have good visible light response properties and photocatalytic properties,and are widely used in applications such as photocatalytic organic synthesis,pollutant degradation,and energy conversion.However,perylene imide and its derivatives generally have the problem of too fast photo-generated electron-hole pair recombination rate,which seriously affects its photocatalytic performance.In this experiment,based on the existing research results,functional group modification,supramolecular self-assembly and heterostructure building of perylene imide molecules were carried out to improve the problems of insufficient visible-light absorption and fast photo-generated electron-hole recombination rate,and its performance and mechanism of catalytic degradation of antibiotics in water under visible-light irradiation were also studied.The main content and main conclusions of this research are as follows:By introducing short linear alkanes with carboxylic acid at the end of the perylene imide molecule to improve its solubility in aqueous solution,and then through acidic induction,it will self-assemble into one-dimensional nanofiber-like supramolecular.Such stable supramolecular have excellent visible-light response ability.In addition,the Ti3C2/PDI heterojunction was prepared through the assemblable properties of PDI supramolecular,and the internal reasons for the improvement of its photocatalytic degradation performance were further studied.The introduction of Ti3C2 MXene nanosheets increases theπ-πstacking degree of the Ti3C2/PDIsm composite system,giving it a largerπ-electron conjugate structure.At the same time,the built-in electric field formed between the Ti3C2 MXene nanosheets and the PDI supramolecules constructs a fast electron channel to accelerate the separation of photogenerated carriers and effectively inhibit the recombination of photogenerated electrons and holes.The apparent rate constants of the photodegradation of Ti3C2/PDIsm composite for tetracycline hydrochloride and rhodamine B are 2.5 times and 7.2 times that of PDI supramolecular monomers,respectively.What’s more,through some characterization techniques such as XRD,FT-IR,SEM,TEM,DRS,EIS,the internal reasons for the improvement of the photocatalytic degradation performance of Ti3C2/PDI composite materials were carried out.The results show that in the Ti3C2/PDIsm composite photocatalyst,the constructed electron acceleration channel can accelerate the separation of photogenerated carriers,effectively inhibit their recombination,and the light quantum efficiency and photocatalytic performance of the composite catalyst have been significantly improved.Furthermore,density functional theory（DFT）calculations also provide strong evidence for the enhanced photocatalytic degradation activity of the Ti3C2/PDIsm structure.This work provides new ideas for the construction of high-efficiency photocatalysts based on PDI organic semiconductor materials. |
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