Synthesis And Catalytic Properties Of One-Dimensional Noble Monometallic/Bimetallic Nanomaterials

In recent years,noble metal nanostructures have attracted much attention due to their potential applications in photonics,electronics,catalysis,biomedicine and other areas.The properties of noble metal nanomaterials are closely related to their compositions,structures,shapes and sizes.Among them,one-dimensional noble metal nanostructures have broader application prospects owning to their unique structure-property relationships.However,compared with noble monometallic nanomaterials,one-dimensional noble bimetallic nanomaterials always exhibit superior catalytic performance due to the synergistic effect between two different metals and geometric effects caused by lattice constants.Based on the extensive applications of one-dimensional noble metal nanostructures in the fields of optics,electricity,magnetism and catalysis.Two different one-dimensional noble metal nanomaterials,silver nanowires(AgNWs)and Pd modified Au nanorods composite,were prepared by different methods,and their catalytic properties were explored respectively.The main research results of this thesis are as follows:1.One-dimensional AgNWs and spherical silver nanoparticles(AgNPs)with high yield,good dispersion and uniformity were prepared and their morphology and structures were characterized.AgNWs could effectively catalyze the three-component coupling reaction of carbon dioxide,secondary amine and propargyl alcohol in the presence of organic base 4-dimethylaminopyridine.Furthermore,AgNWs could be recycled and reused for four times and maintained good morphology structure and catalytic activity.However,spherical AgNPs exhibited undesirable catalytic effect due to agglomeration during the reaction process.Under the optimal experimental condition,we used AgNWs as catalyst to extend the substrates of different propargylic alcohols and secondly amines,and obtained a variety of β-oxopropyl carbamates,which proved the good stability and functional group tolerance of AgNWs.2.Pd modified Au nanorods composite were successfully prepared when using cetyltrimethylammonium bromide as the surfactant and potassium iodide as thestructure-directing reagent,then the co-reduction was performed on the high yield Au decahedral nanoparticles with regular morphology and uniform sizes.Their morphology and structures were analyzed by different characterization methods.By investigating different experimental conditions such as reaction time,temperature,Au decahedral seeds and precursor additions,reducing agent and capping agent concentrations on the growth process,we roughly speculated a possible growth mechanism.Finally,the catalytic performance of Au decahedral nanoparticles and Pd modified Au nanorods composite were investigated by catalyzing the reduction reaction of p-nitrophenol and found that Pd modified Au nanorods composite exhibited better catalytic performance than Au decahedral nanoparticles.