In Situ Single-Nanoparticle Spectroscopy Study of Bimetallic Nanostructure Formation

Bimetallic nanostructures (NSs), with utility in catalysis, are typically prepared using galvanic exchange (GE), but the final catalyst morphology is dictated by the dynamics of the process. In situ single nanoparticle (NP) optical scattering spectroscopy, coupled with ex situ electron microscopy, i...

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Bibliographic Details
Published in:Angewandte Chemie 2016-08, Vol.128 (34), p.10133-10137
Main Authors: Smith, Jeremy G., Chakraborty, Indranath, Jain, Prashant K.
Format: Article
Language:English
Subjects:
Bimetals
Chemistry
Dynamics
Einzelmolekülspektroskopie
Evolution
Heterogeneity
Inclusions
Katalyse
Legierungen
Nanoparticles
Nanopartikel
Nanostructure
Plasmonen
Platinum
Spectroscopy
Spectrum analysis
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Summary:Bimetallic nanostructures (NSs), with utility in catalysis, are typically prepared using galvanic exchange (GE), but the final catalyst morphology is dictated by the dynamics of the process. In situ single nanoparticle (NP) optical scattering spectroscopy, coupled with ex situ electron microscopy, is used to capture the dynamic structural evolution of a bimetallic NS formed in a GE reaction between Ag and [PtCl6]2−. We identify an early stage involving anisotropic oxidation of Ag to AgCl concomitant with reductive deposition of small Pt clusters on the NS surface. At later stages of GE, unreacted Ag inclusions phase segregate from the overcoated AgCl as a result of lattice strain between Ag and AgCl. The nature of the structural evolution elucidates why multi‐domain Ag/AgCl/Pt NSs result from the GE process. The complex structural dynamics, determined from single‐NP trajectories, would be masked in ensemble studies due to heterogeneity in the response of different NPs. Nanopartikel zeigen ihr Metall: Galvanischer Austausch (GE) ist eine wichtige Methode für die Synthese von dimetallischen Nanostrukturen. Mittels Einzelpartikelspektroskopie der Reaktion von Ag mit [PtCl6]2− wird nachgewiesen, dass die Morphologie der gebildeten Nanostruktur das Ergebnis einer dynamischen Abfolge von Strukturtransformationen ist. NP=Nanopartikel.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201604710