Processing core/alloy/shell nanoparticles: Tunable optical properties and evidence for self-limiting alloy growth

Wenjie Wu, Peter N. Njoki, Hyunjoo Han, Hui Zhao, Eric Allan Schiff, Patrick S. Lutz, Louis Solomon, Sean Matthews, Mathew M Maye

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The postsynthetic processing of nanomaterials may allow researchers to reach specific properties, morphologies, or phase regimes that are not accessible by simple synthesis alone. Here, we take advantage of atomic interdiffusion at nanoparticle interfaces to fabricate core/alloy and core/alloy/ shell nanoparticles. Modest temperature changes were found to have profound effects for the interfacial alloying of the confined nanosystem. The alloy formation and subsequent interdiffusion allowed us to tailor nanoparticle composition and ultrastructure, as well as surface plasmon response. This processing step, which involves the layer-by-layer formation of a core/alloy/shell morphology, utilizes hydrothermal annealing provided by automated microwave irradiation to control solute deposition, as well as alloy thickness. As a proof-of-principle system, we employed a Au/Au xAg1-x/Ag nanosystem, due, in large part, to its miscible phase diagram and rich plasmonic behavior. Nanostructure morphology was characterized byTEMand STEM, and compositional analysis was performed via selective area EDX and XPS. The resulting surface plasmon resonance signatures were modeled as a function of alloy or monometallic shell thickness, as well as alloy composition, using the discrete dipole approximationmethod. A proposed shell growth mechanism is described, which involves the competition between a classical ripening system at low temperature and a self-limiting growth at high temperature, the latter of which may be driven by an alloy order-disorder phenomena at the interface. These optical and growth models strongly correlate with the experimental results, namely, that the plasmon resonance is highly tunable on shell thickness and alloy composition and that alloy thickness and interdiffusion are highly tunable by the thermal processing.

Original languageEnglish (US)
Pages (from-to)9933-9942
Number of pages10
JournalJournal of Physical Chemistry C
Volume115
Issue number20
DOIs
StatePublished - May 26 2011

Fingerprint

Optical properties
Nanoparticles
optical properties
nanoparticles
Processing
Nanosystems
Chemical analysis
Interdiffusion (solids)
Microwave irradiation
Order disorder transitions
Surface plasmon resonance
Alloying
surface plasmon resonance
Nanostructured materials
Temperature
alloying
Phase diagrams
Energy dispersive spectroscopy
Nanostructures
solutes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Processing core/alloy/shell nanoparticles : Tunable optical properties and evidence for self-limiting alloy growth. / Wu, Wenjie; Njoki, Peter N.; Han, Hyunjoo; Zhao, Hui; Schiff, Eric Allan; Lutz, Patrick S.; Solomon, Louis; Matthews, Sean; Maye, Mathew M.

In: Journal of Physical Chemistry C, Vol. 115, No. 20, 26.05.2011, p. 9933-9942.

Research output: Contribution to journalArticle

Wu, Wenjie ; Njoki, Peter N. ; Han, Hyunjoo ; Zhao, Hui ; Schiff, Eric Allan ; Lutz, Patrick S. ; Solomon, Louis ; Matthews, Sean ; Maye, Mathew M. / Processing core/alloy/shell nanoparticles : Tunable optical properties and evidence for self-limiting alloy growth. In: Journal of Physical Chemistry C. 2011 ; Vol. 115, No. 20. pp. 9933-9942.
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