| Nanomaterials with nanometer effects have been widely applied in the fields of electronics,machinery and chemical industry,showing great commercial value.Metal clusters,as the star members of nanomaterials,have much attracted much attention in the field of catalysis due to their unique structural properties and electronic properties.Therefore,the research on controllable synthesis methods and catalytic properties of metal clusters is of great significance.Because of the synergistic effect between different metal atoms,the bimetallic cluster may have more advantages in catalytic activity than the single metal cluster.First,the three kinds of metal clusters as catalysts were successfully synthesized.Then the cluster catalysts were characterized by UV-Vis,FT-IR,TEM and other means to explores the structure and chemical properties of clusters.Finally,catalytic performance of the three kinds of metal clusters were tested in catalytic reactions,including benzene methanol oxidation,singlet oxygen of photo-catalytic generation and biomass inulin hydrolysis toward fructose production,to establish the relationship between the structure and catalytic activity of metal clusters.The main contents of this paper are as follows:1.First,CeO2-supported[Au25-x(PET)18-xM]catalyst(M=Cu,Ni,Zn and Co,x=1-4)were successfully synthesized.Then,MADLI-MS,ESI-MS and UV-Vis were used to characterize the cluster catalysts,catalytic activity of these cluster catalysts was studied in benzyl alcohol oxidation test.The results show that the doping of transition metal atom does not change the core structure of Au25(PET)18 clusters,but the catalytic activity and selectivity of the Au25(PET)18 catalysts are greatly affected by the transition metal atom dopants:The CeO2-supported clusters show good catalytic activity and follow the order,[Au25-x(PET)18-xNi]>[Au25-x(PET)18-xCu]>[Au25-x(PET)18-x2ri]>[Au25-x(PET)18-xCo],based on the conversion of alcohol.The[Au25-x(PET)18-xM]clusters also show different catalytic selectivity.The[Au25-x(PET)18-xZn]and[Au25-x(PET)18-xCo]catalysts yield benzaldehyde as the main product,the[Au25-x(PET)18-xCu]yields benzaldehyde and benzyl acid,and the[Au25-x(PET)18-xNi]catalyst to benzyl acid.2.Based on the catalytic properties of metal clusters could be greatly changed by metal atom dopants,a new type of[CuW]bimetallic cluster catalyst based on tungstate was synthesized.FT-IR,UPS,UV-Vis,EA and other means were used to characterize this cluster.The study shows that the cluster is an excellent solid acid catalyst,which has excellent catalytic performance for the catalytic hydrolysis of biomass inulin to the preparation of fructose.The cluster catalyst gave very high conversion(a decent 100%)and selectivity(ca.90%),under relatively mild reaction conditions(e.g.,in aqueous solution at 80℃),and showed an excellent repetition of availability.3.A new method has been developed to obtain a[CoMo]bimetallic cluster catalyst with atomic dispersion,which has been characterized by means of FT-IR,ESI-MS,UV-Vis,XPS,TGA and so on.The results indicate that the cluster is a typical n-type inorganic semiconductor material,which has excellent reversible double electron redox property,and has the characteristics of photocatalysis,electrocatalysis and photoelectricity catalysis.The experimental results show that the[CoMo]bimetallic cluster is more effective than the traditional dye photosensitizer methylene blue(NMB)for the photo catalytic molecular oxygen,and it is a very excellent photocatalyst. |
