Dissociative Water Adsorption on Gas-Phase Titanium Dioxide Cluster Anions Probed with Infrared Photodissociation Spectroscopy

Marissa L. Weichman, Sreekanta Debnath, John T. Kelly, Sandy Gewinner, Wieland Schöllkopf, Daniel M. Neumark, Knut R. Asmis

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Gas-phase complexes of water on small titanium oxide clusters are model systems to examine the molecular-level mechanism of dissociative water adsorption at defect sites on bulk titania surfaces. Here, we report infrared photodissociation (IRPD) spectra for [(TiO2)n(D2Om)] clusters with n = 2–4 and m = 1–3; the clusters are tagged with weakly-bound D2 so that only single photon absorption is required for photodissociation. Vibrational features are reported in the spectral windows of 400–1200 and 2600–3000 cm− 1 , capturing both fingerprint cluster modes and O–D stretching modes. The IRPD spectra are interpreted with the aid of ωB97X-D/aug-cc-pVDZ density functional theory calculations. We conclusively assign the IRPD spectra of the n = 2, m = 1,2 and n = 3, m = 1–3 clusters to global minimum-energy structures containing dissociatively adsorbed water. We also provide insight into the more complicated spectroscopy of the n = 4 clusters, which show possible contributions from a kinetically trapped reactive intermediate in addition to the global minimum-energy isomer. From this work, we can draw conclusions about the size dependence and site-specificity of (TiO2)n cluster reactivity.

Original languageEnglish (US)
Pages (from-to)92-105
Number of pages14
JournalTopics in Catalysis
Volume61
Issue number1-2
DOIs
StatePublished - Mar 1 2018

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

Keywords

  • Density functional theory
  • Dissociative water adsorption
  • Infrared photodissociation spectroscopy
  • Metal oxide clusters
  • Titanium dioxide
  • Water splitting catalysis

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