Synthesis And Photocatalytic Properties Of Titanium Oxide Clusters

TiO2 nanoparticles have good photocatalytic performance and play an important role in catalytic degradation of pollutants and absorption and conversion of sunlight.Crystal titanium oxide clusters not only have similar composition,structure and photocatalytic performance,but also have a clear structure that can be characterized that TiO2 nanoparticles do not have,so that they can be used as a molecular model of TiO2 combined with DTF theoretical calculation to obtain accurate electronic structure and interface structure information,which is helpful for the study of structure-activity relationship.Further elucidation of the photocatalytic reaction mechanism provides the possibility that titanium oxide clusters modified by ligands or doped by metals have higher sunlight absorption efficiency and better catalytic performance due to their smaller band gap.Organic carboxylic acids are the most common surface modified ligands,which can increase the stability and catalytic activity of clusters.Metal-doped titania clusters have been reported,that is,compounds containing both TixOy and MxOy(M=metal)structures in the same molecule have rarely been produced or used for photocatalysis.Based on the precise structure of titanium oxide clusters,as a model to better study their synthesis,structure,electronic structure,photoelectric response characteristics and photocatalytic reaction application and mechanism.In this paper,we synthesized two titania clusters doped with high nuclear number of bismuth ions,and found that they showed excellent catalytic activity in the photocatalytic reaction,so as to study the catalytic mechanism.The content of this paper is divided into the following three parts:(1)In the first part,we first introduced the research background and progress of titanium oxide clusters,and introduced the research process of titanium oxide clusters after construction modification.Then we introduced two kinds of photocatalytic reactions,and explained the significance of their occurrence and related reaction mechanism research.Finally,the significance of this topic is put forward,and the research content of this paper is summarized.(2)In the second part,a new type of Ti-Bi mixed metal oxide cluster Ti18Bi4O29Bz26·8MeCN was synthesized by solvothermal method.Due to the presence of Ti4+and Bi3+ on its surface,it showed high catalytic activity in the cycloaddition reaction between CO2 and epoxide.The yield and selectivity of carbon dioxide cycloaddition under different conditions were investigated,and the catalytic reaction mechanism was studied.(3)In the third part,a high-nucleated titanium-oxide cluster H2Ti19Bi2(μ3-O)20(μ2-O)9(PhCOO)26·2MeCN doped with metal bismuth ions was synthesized by a one-pot solvothermal method.The structure of the cluster was characterized by X-ray diffraction instruments.It is a novel cage structure.Bi3+is an active site embedded on the surface,so it can be used as a catalyst for photoreaction.We studied the synthesis,structure,electronic structure,photoelectric response characteristics of the cluster and its application in photocatalytic benzyl alcohol reaction,and discussed the photocatalytic mechanism.