Study On Metal Sulfide Composites For Photooxidation Coupling Of Benzylamine And Photocatalytic Dehydrogenation Of Tetrahydroisoquinoline

The photocatalytic technology has received extensive attentions from researchers due to its green and pollution-free advantages.From the researches of water photo-decomposition with Ti O₂ on,semiconductor materials have shown excellently photocatalytic performance in the field of photocatalysis.The application of photocatalytic technology to organic reactions meets the requirements of green chemistry and sustainable development.We all know that the oxidation reaction of nitrogen-containing organics has been extensively studied because its target products can be used in the synthesis of pesticides,intermediate materials for fine chemicals,and exhibiting a certain potential for hydrogen storage.The occurrence of photocatalytic organic reactions is a heterogeneous catalysis process,which is conducive to the recovery and reuse of photocatalysts.Due to the adjustable band gap of semiconductor materials,selective synthesis of organic reactions can be achieved.However,semiconductor materials have always been limited by the recombination efficiency of photogenerated carriers and the photon utilization rate.How to modify the semiconductor materials to meet the needs of photocatalytic organic reactions is the most important problem to be solved at present.Therefore,the design,research and synthesis of new and efficient semiconductor photocatalysts is imminent.In inorganic semiconductor materials,metal sulfides have received wide attention from researchers because they are easily modified and have a wide absorption boundary for visible light.However,shortcomings such as low photogenerated carrier separation efficiency limit its further application.Therefore,it is important to modify the sulfide semiconductor material to further improve its photocatalytic activity.In this paper,we designed and synthesized metal sulfides and their composite materials,and applied them to the photocatalytic dehydrogenation reaction of1,2,3,4-tetrahydroisoquinoline and the photocatalytic benzylamine oxidative coupling reaction.During the experiment,the effect of pristine property,the morphology,the solid solution construction and the heterojunction formation of the synthesized semiconductor material on the photocatalytic reaction activity was well explored.The research content is as follows:1.ZnIn₂S₄ photocatalyst is synthesized by one-step hydrothermal method.In the reaction process,different solvents are used to control the nano-petal-like and tremella-like morphology of ZnIn₂S₄,and it is used in 1,2,3,4-tetrahydroisoquinoline receptor-free catalytic dehydrogenation reaction.The experimental results show that under air conditions,using DMF as solvent and after 7 hours of visible light irradiation,ZnIn₂S₄ containing sulfur vacancies in tremella shape has high photocatalytic activity.At the same time,we also proposed a possible mechanism for the reaction and the cyclic experiment proved that the catalyst has high stability.2.It is well-known that CdS semiconductor materials show strong ability to absorb visible light,but the separation efficiency of photogenerated carriers is low.Therefore,it retains the advantages of CdS by introducing zinc ions to construct a solid solution and also improving the efficiency of carrier separation at the same time.The experimental results prove that Zn_0.2Cd_0.8S has high catalytic activity for the benzylamine coupling reaction.By introducing a small amount of graphene and MoS₂,its photocatalytic activity can be further improved.Therefore,we designed and synthesized Zn_0.2Cd_0.8S/MoS₂/GO ternary composite material and applied it to the photocatalysis of 1,2,3,4-tetrahydroisoquinoline.The heterojunction formed between Zn_0.2Cd_0.8S and MoS₂ effectively reduces the recombination efficiency of carriers.The presence of a small amount of graphene not only increases the active sites of the reaction,but also promotes the transfer of electrons.The synergy of MoS₂ and GO catalyst makes it have a better photocatalytic effect.The cycle experiment proved that the catalyst has high stability and cyclability.3.1D-2D CdS/Bi₄O₅Br₂ composite material was synthesized by in-situ solvothermal method.The formation of effective heterojunction at the contact interface of CdS/Bi₄O₅Br₂ material is beneficial to the separation of photogenerated carriers.Then the synthesized CdS/Bi₄O₅Br₂ material is applied to the photocatalytic coupling reaction of benzylamine,and CdS nanorods is also simply used to the photocatalytic dehydrogenation reaction of 1,2,3,4-tetrahydroisoquinoline.Through active species capture experiments,the reaction mechanisms of the two organic reactions were studied and possible reaction mechanisms were proposed.