Surface structure and composition of Au-Rh bimetallic nanoclusters on TiO2(110)

A LEIS and STM study

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Gold, rhodium, and their coadsorbed layers were prepared on a nearly stoichiometric titania surface by physical vapor deposition (PVD) and were characterized by low-energy ion scattering (LEIS) and scanning tunneling microscopy (STM). It was found that because of the strong tendency of Au segregation in the Au-Rh bimetallic system, Rh atoms that impinged onto Au clusters pregrown on TiO2(110) became covered by gold atoms by place exchange or surface diffusion even at room temperature. The incorporation of rhodium led to a slight enlargement of gold clusters indicated by STM and to an increase in the number of Au atoms on the outermost layer of metal clusters evidenced by LEIS. At the same time, separate Rh clusters were also formed on the free oxide surface. The observed effect on the bimetallic nanoclusters is attributed to the different surface free energies of metals. For Au, this value is much smaller than for Rh, which provides a driving force for the bimetallic clusters to be covered by gold atoms. Annealing experiments revealed that monometallic Rh clusters are encapsulated at ∼750 K by the oxide. Encapsulation by titania is negligible up to 900 K for the bimetallic nanoparticles almost completely covered by Au.

Original languageEnglish
Pages (from-to)18011-18016
Number of pages6
JournalJournal of Physical Chemistry C
Volume112
Issue number46
DOIs
Publication statusPublished - Nov 20 2008

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Nanoclusters
ion scattering
Scanning tunneling microscopy
nanoclusters
Surface structure
Gold
scanning tunneling microscopy
Scattering
Ions
Atoms
Rhodium
gold
Oxides
rhodium
Titanium
Metals
atoms
titanium
energy
Surface diffusion

ASJC Scopus subject areas

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

Cite this

Surface structure and composition of Au-Rh bimetallic nanoclusters on TiO2(110) : A LEIS and STM study. / Óvári, L.; Bugyi, L.; Majzik, Zsolt; Berkó, A.; Kiss, J.

In: Journal of Physical Chemistry C, Vol. 112, No. 46, 20.11.2008, p. 18011-18016.

Research output: Contribution to journalArticle

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