Controlled Synthesis Of Ag/Pt Nanostructures And Their Catalytic Properties

Bimetallic nanostructures have received increasing interest owing to the electronic, optical,and catalytic properties, which shows potential applications in fuel cells, diagnosis,surface-enhanced Raman spectroscopy and catalysis. Bimetallic nanostructures materials exhibitmultiple functionalities for applications. A key challenge to improve the performance of thebimetallic nanostructures materials is the development of controlling the structures. In this paper,the bimetal nanoparticles with different structures such as core@shell structure and hollowstructure decorated on the titanate nanowires were prepared by simple wet chemical method. Theinfluence of this nanocomposite with controlled bimetallic nanostructures was studied. Theresults achieved in this paper were listed as follows:1. TiO2NW@hollow Ag*/Pt nanostructures were synthesized. In the synthesis, silvernanoparticles were first grown on titanate nanowires, and then PtO shells coated on the Agnanoparticle to form the TiO2NW@Ag*NP@PtO nanostructures. The hollow Ag*/PtOxnanostructures were gained from Ag*NP@PtO nanostructures by outward diffusion of superfineAg nanoparticles from Ag*NP core to PtO shell in H2O2solution. Finally, the hollow Ag*/Ptnanostructures were successfully synthesized by reduction of hollow Ag*/PtOxnanostructures.For TiO2NW@Ag*NP@PtO nanostructures, the concentration of K2PtCl4was studied. With anincrease in the amount of Pt source in the precursor solutions, the PtO shell thickness wasgradually increased and the Pt/Ag molar ratio was simultaneously increased. The reaction of theTiO2NW@Ag*NP@PtO nanostructures with H2O2results in the TiO2NW@hollow Ag*/PtOxnanostructures. H2O2play a vital role in diffusing the superfine AgNP from Ag*NP core to PtOshell. Meanwhile, the PtO shells were in situ oxidized to the PtO2in the Ag*/PtOxshell by H2O2.NaBH4was used to reduction of PtOxto Pt in catalysts. Catalytic activities of catalysts(TiO2NW@Ag*NP@Pt catalyst and TiO2NW@hollow Ag*/Pt catalyst) for the reduction of4-nitrophenol (4-NP) to4-aminophenol (4-AP) by NaBH4were investigated. Compared withTiO2NW@Ag*NP@Pt catalysts, TiO2NW@Ag*NP@Pt catalyst with thin shell exhibited highcatalytic activity due to the AgNP exposure and the synergistic effect between Ag and Pt. With increasing the reaction time (reaction between TiO2NW@Ag*NP@PtO catalyst and H2O2solution), the rate of reduction reaction first rise and then drop, indicating that the Pt sites andbimetallic interfaces were changed due to the superfine AgNP diffusion. The TiO2NW@hollowAg*/Pt catalyst are capable for efficient decomposition of organic contaminants for long-lastingand recycle usage due to the titanate nanowires with one-dimensional nanostructures.2. TiO2NW@hollow Ag/AgPt nanostructures were synthesized. In the synthesis, silvernanoparticles were first grown on titanate nanowires. The reaction of TiO2NW@AgNPnanostructures, ascorbic acid and platinum precursor results in the TiO2NW@hollow Ag/AgPtnanostructures with flake structures. The TiO2NW@hollow Ag/AgPt nanostructures withdifferent structures were synthesized by controlling the concentration of Pt source. The activityof catalysts for the reduction of4-NP to4-AP by NaBH4was investigated. TiO2NW@hollowAg/AgPt nanostructures with flake structures showed excellent catalytic activity due to theirstructure, bimetallic interfaces and the hydrophobic nature of titanate nanowires. Moreover, theTiO2NW@hollow Ag/AgPt catalyst is easy to recycle due to titanate nanowires.