Adsorption and diffusion of a single Pt atom on γ-Al2O3 surfaces

N. Aaron Deskins, Donghai Mei, Michel Dupuis

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Motivated to better understand the interactions between Pt and γ-Al2O3 support, the adsorption and diffusion of a single Pt atom on γ-Al2O3 was studied using density functional theory. Two different surface models with atoms of various coordination (3-5) were used, one derived from a defected spinel structure, and another derived from the dehydration of boehmite (AlOOH). Adsorption energies are similar for the two surfaces, about -2 eV for the most stable sites, and involve Pt binding to surface O atoms. An unusually strong trapping geometry whereby Pt moves into the surface was identified over the boehmite-derived surface. In all cases the surface transfers ∼0.2-0.3 e- to the Pt atom. The bonding is explained as being a combination of charge transfer between the surface and Pt atom, polarization of the metal atom, and some weak covalent bonding. The similarity of the two surfaces is attributed to the similar local environments of the surface atoms, as corroborated by geometry analysis, density of states, and Bader charge analysis. Calculated activation barriers (0.3-0.5 eV) for the defected spinel surface indicate fast diffusion and a kinetic Monte Carlo model incorporated these barriers to determine exact diffusion rates and behavior. The kinetic Monte Carlo results indicate that at low temperatures (<500 K) the Pt atom can become trapped at certain surface regions, which could explain why the sintering process is hindered at low temperature. Finally we modeled the adsorption of Pt on hydrated surfaces and found adsorption to be weaker due to steric repulsion and/or decreased electron-donating ability of the surface.

Original languageEnglish
Pages (from-to)2793-2807
Number of pages15
JournalSurface Science
Volume603
Issue number17
DOIs
Publication statusPublished - Sep 1 2009

Keywords

  • Ab initio quantum chemical methods and calculations
  • Aluminum oxide
  • Atom-solid interactions
  • Monte Carlo simulations
  • Semiconducting surfaces

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Adsorption and diffusion of a single Pt atom on γ-Al<sub>2</sub>O<sub>3</sub> surfaces'. Together they form a unique fingerprint.

  • Cite this