| Developing excellent photocatalysts to make full use of solar energy to achieve industrial production is an effective method to deal with various energy and environmental problems.How to improve the separation efficiency of photogenerated electrons and holes is the main goal to improve the activity of semiconductor photocatalysts.BiOCl has attracted much attention because of its unique layered structure and high chemical stability.However,as a wide band gap semiconductor,BiOCl can not effectively use visible light,which greatly hinders its application in various photocatalytic reactions under visible light.Constructing composite materials is an important means to improve the performance of semiconductor photocatalysts.A large number of studies on BiOCl composite catalysts have been reported,however they are more used in the field of environmental protection and sewage treatment.The application of BiOCl and its composites is rare in the field of organic synthesis using photocatalytic technology,which has been widely concerned by scientists in recent years.In addition,most of the matrix used to construct BiOCl composites come from chemical production,which is not conducive to the green and sustainable chemical requirements of practical application.It is worth noting that cellulose,as a source rich,natural and renewable polymer,can anchor nanoparticles due to the abundant hydroxyl groups.Among them,cellulose nanocrystal(CNC)also has a large specific surface,which can improve the stability and dispersion of the catalyst and enhance the light effect,it can realize the efficient utilization of visible light.Based on the above considerations,this paper aims to develop a new BiOCl-based catalyst and realize its efficient modification to prepare catalysts with good visible light absorption and photocatalytic properties,and expand their wide applications.This paper focuses on the synthesis method and application of CNC supported BiOCl.The full text is mainly divided into the following five parts:1.At room temperature,CNC with abundant hydroxyl groups and high specific surface area is used as the matrix to construct composite(BiOCl/CNC)to improve the photocatalytic performance of BiOCl.BiOCl/CNC is comprehensively characterized by a series of tests.The results show that the morphology of BiOCl/CNC changes from layered overlapped smooth nanosheets of BiOCl to three-dimensional crossed nanosheets,and the high proportion exposure of(110)crystal surface,the increase of specific surface area and the increase of oxygen vacancy in BiOCl/CNC,which are conducive to improve the catalytic performance of the catalyst in photocatalytic reaction.Therefore,the synthesis of the composite catalyst has important reference significance for designing modified BiOCl,expanding its application in the field of photocatalysis and constructing composite photocatalyst with CNC as matrix.2.The application of BiOCl/CNC in the photocatalytic degradation of Rhodamine B(Rh B)are studied in this chapter.The effects of different conditions on the degradation reaction are systematically investigated and the results showes that BiOCl/CNC exhibites good catalytic performance and stability under simulated sunlight.The results showed that BiOCl/CNC shows excellent catalytic performance and stability under simulated sunlight.When irradiated with natural sunlight,the degradation effect remains good,and it can still maintain good catalytic performance when the reaction system is enlarged 10 times.Then,the possible intermediates and pathways of BiOCl/CNC photocatalytic degradation of Rh B are explored by gas chromatography-mass spectrometry.The active species in the degradation process and the photosensitization of Rh B are verified by free radical acquisition experiment.Combined with the key role of oxygen vacancy in the catalyst,the reasonable degradation mechanism is deduced.The content of this chapter provides an important experimental basis for CNC as BiOCl carrier to enhance the photocatalytic performance.It not only provides a research model for the study of BiOCl sensitization,but also opens up a new idea for industrial Rh B wastewater treatment.3.In this chapter,the auto-oxidative coupling reaction of benzylamine is used as the target reaction to preliminarily expand the wide application of BiOCl/CNC in organic synthesis.Firstly,benzylamine oxidation is used as a template and a household stable and energy-saving LED lamp is used as the light source.The products composition is analysised by gas chromatography(GC),and the reaction conditions are optimized.Under the optimal conditions,the photocatalytic performance of BiOCl/CNC for benzylamine oxidation is systematically studied,and it shows good adaptability to the reactants of ten different functional groups.The experimental results show that the catalyst has excellent stability in benzylamine coupling reaction.The reaction mechanism is reasonably speculated by the free radical trapping experiment and the identification of the by-product hydrogen peroxide.The work in this chapter is helpful to further understand the importance of crystal surface regulation and oxygen vacancy of BiOCl based composites,and establish a new green method for the synthesis of n-benzylene butylamine.4.BiOCl/CNC is used as catalyst to realize the photocatalysis of arylacetylene sulfone compounds for the first time in this chapter.Firstly,phenylpropioic acid and sodium ptoluenesulfinate are used as templates for reaction,when iodine is added and tetrahydrofuran is used as solvent.The experimental conditions are optimized under the household LED lamp.Subsequently,the substrate expansion and stability studies are completed under the optimal conditions,which showed that the reaction has good adaptability to the substrate,the yield can reach as high as 96%.And the BiOCl/CNC has good recycling ability in the reaction system,which greatly improved the economy of the synthesis method.Finally,a possible reaction mechanism is proposed through a series of control experiments and radical trapping experiments.Compared with the traditional synthesis methods,this method not only broadens the application field of BiOCl-based composites,but also provides an economical and efficient method for the green synthesis of arylacetylene sulfones.5.Based on the work of previous chapter,a metal-free and oxidant-free iodine-promoted sulfonylation of arylacetylenic acid and sodium sulfinates under visible light is established.A series of arylacetylene sulfones are synthesized efficiently by using cheap and easy-toobtain elemental iodine under the irradiation of household LED lamps.The substrate expansion experiment shows that the method has good functional group compatibility,and the yield of the product is as high as 93%.Through a series of control experiments and intermediate capture experiments,the structure of the main intermediate is finally determined and the mechanism is explored mainly focusing on the important role of molecular iodine in it.This work not only provides a green synthesis method for the preparation of arylacetylene sulfone,but also provides a new insight into the role of molecular iodine in photocatalytic organic synthesis. |
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