Synthesis,Characterization And Heterogeneous Photocatalytic Performance Of Functionalized Covalent Organic Materials

At present,environmental pollution and energy crisis are getting more and more attention.Therefore,scientists are seeking effective ways to solve this problem.From the perspective of chemical materials,designing and synthesizing efficient,green photocatalysts is one of the most effective solutions.It is known that in the field of photocatalysis,homogeneous photocatalysts have higher activity in catalytic reaction systems than heterogeneous photocatalysts,but it is difficult to separate them from the reaction system.The recovery costs are high,the recycling efficiency is low and pollute the environment.People want to find high efficiency,low cost,minimal environmental impact and energy consumption methods to catalyze the organic reaction driven by visible light.Therefore,it is of great significance to develop an efficient and environmentally friendly heterogeneous photocatalyst.Covalent organic materials have been widely used in the fields of gas storage,separation,optoelectronics,catalysis,and sensing due to their high stability and low relative density,which has caused great concern among scientific researchers.In the third chapter of this thesis,a method of synthesizing a covalent organic framework based on hydrazone bonds was developed by using the method of imine condensation of dihydrazide and trialdehyde.Through the characterization of its structure,the material has high crystallinity,good porosity and gas adsorption capacity,the specific surface area up to 1501 m²g^–1.In addition,the material is also highly thermally stable and chemically stable.In conventional organic solvents,strong acids and strong bases,the crystallinity remains unchanged.This material can act as a heterogeneous photocatalyst that catalyzes cross-dehydrogenative coupling reaction.Experiments show that the material has good photocatalytic activity and a certain range of substrate applicability,and has easy recovery and recyclability.This material,as a heterogeneous catalyst,demonstrates the great potential of porous materials in the field of photocatalysis.In the fourth chapter of this thesis,a boron difluoride-based covalent organic polymer was prepared in a donor-acceptor ordered arrangement by the condensation reaction of boron difluoride derivative and trialdehyde.The material has high thermal stability,chemical stability and photophysical stability,and can effectively capture the light source.The study of heterogeneous photocatalytic activity shows that the material has high activity and wide applicability to photocatalytic reaction.It can efficiently catalyze the oxidative coupling reaction of primary amines at room temperature and the cross-dehydrogenation coupling reaction of a range of substrates.In addition,photocatalytic cycling experiments show that the material also has strong recycling and can maintain good photocatalytic activity after four cycles.