title: Synthesis and catalytic properties of Au-Pd nanoflowers.
abstract: Reduction of Pd ions by hydroquinone in the presence of gold nanoparticles and polyvinylpyrrolidone resulted in the formation of nanoflowers with a Au core and Pd petals. Addition of HCl to the synthesis halted the reduction by hydroquinone and enabled the acquisition of snapshots of the nanoflowers at different stages of growth. TEM images of the reaction after 10 s show that the nanoflower morphology resulted from the homogeneous nucleation of Pd clusters in solution and their subsequent attachment to gold seeds coated with a thin (0.8 ± 0.1 nm) shell of Pd. UV-visible spectra also indicate Pd clusters formed in the early stages of the reaction and disappeared as the nanoflowers grew. The speed at which this reaction can be halted is useful not only for producing a variety of bimetallic nanostructures with precisely controlled dimensions and morphologies but also for understanding the growth mechanism of these structures. The ability of the AuPd core-shell structure to catalyze the Suzuki coupling reaction of iodobenzene to phenylboronic acid was probed and compared against the activity of Pd nanocubes and thin-shelled AuPd core-shell nanoparticles. The results of this study suggest that Suzuki coupling was not affected by the surface structure or subsurface composition of the nanoparticles, but instead was primarily catalyzed by molecular Pd species that leached from the nanostructures.
authors.affiliation: Department of Chemistry, Duke University, 124 Science Drive, Box 90354, Durham, North Carolina 27708, USA.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Xu
authors.forename: Adria R
authors.initials: AR
authors.lastname: Wilson
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Rathmell
authors.forename: Jane
authors.initials: J
authors.lastname: Howe
authors.forename: Miaofang
authors.initials: M
authors.lastname: Chi
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Wiley