Defect-Induced Water Bilayer Growth on Anatase TiO2(101)

A Schaefer; V Lanzilotto; U B Cappel; P Uvdal; A Borg; A Sandell

doi:10.1021/acs.langmuir.8b01925

Defect-Induced Water Bilayer Growth on Anatase TiO₂(101)

Langmuir. 2018 Sep 18;34(37):10856-10864. doi: 10.1021/acs.langmuir.8b01925. Epub 2018 Sep 7.

Authors

A Schaefer¹, V Lanzilotto², U B Cappel², P Uvdal³, A Borg⁴, A Sandell²

Affiliations

¹ Department of Chemistry and Chemical Engineering, and Competence Centre for Catalysis , Chalmers University of Technology , 41296 Gothenburg , Sweden.
² Department of Physics and Astronomy , Uppsala University , P.O. Box 516, SE-75120 Uppsala , Sweden.
³ Chemical Physics, Department of Chemistry , Lund University , P.O. Box 124, SE-221 00 Lund , Sweden.
⁴ Department of Physics , NTNU - Norwegian University of Science and Technology , NO-7491 Trondheim , Norway.

PMID: 30153024
DOI: 10.1021/acs.langmuir.8b01925

Abstract

Preparing an anatase TiO₂(101) surface with a high density of oxygen vacancies and associated reduced Ti species in the near-surface region results in drastic changes in the water adsorption chemistry compared to adsorption on a highly stoichiometric surface. Using synchrotron radiation excited photoelectron spectroscopy, we observe a change in the water growth mode, from layer-by-layer growth on the highly stoichiometric surface to bilayer growth on the reduced surface. Furthermore, we have been able to observe Ti³⁺ enrichment at the surface upon water adsorption. The Ti³⁺ enrichment occurs concomitant with effective water dissociation into hydroxyls with a very high thermal stability. The water bilayer on the reduced surface is thermally more stable than that on the stoichiometric surface, and it is more efficient in promoting further water dissociation upon heating. The results thus show how the presence of subsurface defects can alter the wetting mechanism of an oxide surface.

Publication types

Research Support, Non-U.S. Gov't