title: Surface Segregated AgAu Tadpole-Shaped Nanoparticles Synthesized Via a Single Step Combined Galvanic and Citrate Reduction Reaction.
abstract: New AgAu tadpole nanocrystals were synthesized in a one-step reaction involving simultaneous galvanic replacement between Ag nanospheres and AuCl4(-)(aq.) and AuCl4(-)(aq.) reduction to Au in the presence of citrate. The AgAu tadpoles display nodular polycrystalline hollow heads, while their undulating tails are single crystals. The unusual morphology suggests an oriented attachment growth mechanism. Remarkably, a 1 nm thick Ag layer was found to segregate so as to cover the entire surface of the tadpoles. By varying the nature of the seeds (Au NPs), double-headed Au tadpoles could also be obtained. The effect of a number of reaction parameters on product morphology were explored, leading to new insights into the growth mechanisms and surface segregation behavior involved in the synthesis of bimetallic and anisotropic nanomaterials.
authors.affiliation: Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo-SP (Brazil).
authors.forename: Anderson G M
authors.initials: AG
authors.lastname: da Silva
authors.affiliation: School of Materials, The University of Manchester, Manchester, M13 9PL (UK).
authors.forename: Edward A
authors.initials: EA
authors.lastname: Lewis
authors.affiliation: Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo-SP (Brazil).
authors.forename: Thenner S
authors.initials: TS
authors.lastname: Rodrigues
authors.affiliation: School of Materials, The University of Manchester, Manchester, M13 9PL (UK).
authors.forename: Thomas J A
authors.initials: TJ
authors.lastname: Slater
authors.affiliation: Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo-SP (Brazil).
authors.forename: Rafael S
authors.initials: RS
authors.lastname: Alves
authors.affiliation: School of Materials, The University of Manchester, Manchester, M13 9PL (UK). sarah.haigh@manchester.ac.uk.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Haigh
authors.affiliation: Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo-SP (Brazil). camargo@iq.usp.br.
authors.forename: Pedro H C
authors.initials: PH
authors.lastname: Camargo
keywords: alloys; gold; materials science; nanostructures; silver