title: Galvanic Replacement Coupled to Seeded Growth as a Route for Shape-Controlled Synthesis of Plasmonic Nanorattles.
abstract: Shape-controlled synthesis of metal nanoparticles (NPs) requires mechanistic understanding toward the development of modern nanoscience and nanotechnology. We demonstrate here an unconventional shape transformation of Au@Ag core-shell NPs (nanorods and nanocubes) into octahedral nanorattles via room-temperature galvanic replacement coupled with seeded growth. The corresponding morphological and chemical transformations were investigated in three dimensions, using state-of-the-art X-ray energy-dispersive spectroscopy (XEDS) tomography. The addition of a reducing agent (ascorbic acid) plays a key role in this unconventional mechanistic path, in which galvanic replacement is found to dominate initially when the shell is made of Ag, while seeded growth suppresses transmetalation when a composition of Au:Ag (∼60:40) is reached in the shell, as revealed by quantitative XEDS tomography. This work not only opens new avenues toward the shape control of hollow NPs beyond the morphology of sacrificial templates, but also expands our understanding of chemical transformations in nanoscale galvanic replacement reactions. The XEDS electron tomography study presented here can be generally applied to investigate a wide range of nanoscale morphological and chemical transformations.
authors.affiliation: Bionanoplasmonics Laboratory, CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastian, Spain.|Departamento de Química Física, Universidade de Vigo , 36310 Vigo, Spain.
authors.forename: Lakshminarayana
authors.initials: L
authors.lastname: Polavarapu
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: Daniele
authors.initials: D
authors.lastname: Zanaga
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Altantzis
authors.affiliation: Departamento de Química Física, Universidade de Vigo , 36310 Vigo, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rodal-Cedeira
authors.affiliation: Departamento de Química Física, Universidade de Vigo , 36310 Vigo, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pastoriza-Santos
authors.affiliation: Departamento de Química Física, Universidade de Vigo , 36310 Vigo, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pérez-Juste
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: Bals
authors.affiliation: Bionanoplasmonics Laboratory, CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastian, Spain.|Departamento de Química Física, Universidade de Vigo , 36310 Vigo, Spain.|Ikerbasque, Basque Foundation for Science , 48013 Bilbao, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán