Growth of gold on a pinwheel TiO∼1.2 encapsulation film prepared on rhodium nanocrystallites

Research output: Contribution to journalArticle

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Abstract

Rh nanoparticles of 50-100 nm diameter and 20-40 atomic layer thickness with a (111) flat top facet parallel to the support surface were grown on a TiO2(110) surface via physical vapor deposition (PVD) at room temperature (RT) followed by annealing at 1050 K. These nanoparticles were completely encapsulated by an ordered hexagonal pinwheel TiO∼1.2 ultrathin oxide (w-TiO-UTO) film. STM, XPS, and low energy ion scattering (LEIS) methods were used to characterize the postdeposition of gold and the effects of annealing on the Au/w-TiO-UTO/Rh-particle system. The adlayer exhibits 3D growth and Rh-Au bond formation at 500 K. The 3D Au nanoparticles of 2-3 nm diameter and ∼1 nm height are partially covered by TiOx species at RT and sinter via an Ostwald-ripening in the range of 500-800 K. The adparticles are gradually getting free of TiOx decoration, and at around 900 K they exhibit a double layer height with 2D character. Two different arrangements were found for these Au particles: (i) a compressed Au(111)-(1 × 1) and (ii) a reconstructed Au(111)-(2 × 1), both of them pseudomorphic with the Rh lattice underneath. Above 900 K, the thickness of these 2D particles tends to become a single layer, while they spread out and form a continuous gold layer on the Rh nanoparticles. This behavior indicates a thermally activated replacement of the w-TiO-UTO film by an Au ultrathin layer. The gold layer is stable up to 1000 K, where extended 1D interfaces are formed between gold and w-TiO-UTO layers. (Figure Presented)

Original languageEnglish
Pages (from-to)14545-14554
Number of pages10
JournalLangmuir
Volume30
Issue number48
DOIs
Publication statusPublished - Dec 9 2014

Fingerprint

Nanocrystallites
Rhodium
rhodium
Encapsulation
Gold
gold
Nanoparticles
nanoparticles
Annealing
Ostwald ripening
Physical vapor deposition
Oxides
X ray photoelectron spectroscopy
Scattering
Ions
annealing
Temperature
ion scattering
room temperature
flat surfaces

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Growth of gold on a pinwheel TiO∼1.2 encapsulation film prepared on rhodium nanocrystallites. / Gubó, R.; Óvári, L.; Kónya, Z.; Berkó, A.

In: Langmuir, Vol. 30, No. 48, 09.12.2014, p. 14545-14554.

Research output: Contribution to journalArticle

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abstract = "Rh nanoparticles of 50-100 nm diameter and 20-40 atomic layer thickness with a (111) flat top facet parallel to the support surface were grown on a TiO2(110) surface via physical vapor deposition (PVD) at room temperature (RT) followed by annealing at 1050 K. These nanoparticles were completely encapsulated by an ordered hexagonal pinwheel TiO∼1.2 ultrathin oxide (w-TiO-UTO) film. STM, XPS, and low energy ion scattering (LEIS) methods were used to characterize the postdeposition of gold and the effects of annealing on the Au/w-TiO-UTO/Rh-particle system. The adlayer exhibits 3D growth and Rh-Au bond formation at 500 K. The 3D Au nanoparticles of 2-3 nm diameter and ∼1 nm height are partially covered by TiOx species at RT and sinter via an Ostwald-ripening in the range of 500-800 K. The adparticles are gradually getting free of TiOx decoration, and at around 900 K they exhibit a double layer height with 2D character. Two different arrangements were found for these Au particles: (i) a compressed Au(111)-(1 × 1) and (ii) a reconstructed Au(111)-(2 × 1), both of them pseudomorphic with the Rh lattice underneath. Above 900 K, the thickness of these 2D particles tends to become a single layer, while they spread out and form a continuous gold layer on the Rh nanoparticles. This behavior indicates a thermally activated replacement of the w-TiO-UTO film by an Au ultrathin layer. The gold layer is stable up to 1000 K, where extended 1D interfaces are formed between gold and w-TiO-UTO layers. (Figure Presented)",
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