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Title: Structure of Rutile TiO 2 (110) in Water and 1 Molal Rb+ at pH 12: Interrelationship Among Surface Charge, Interfacial Hydration Structure, and Substrate Structural Displacements

Abstract

The rutile (110)-aqueous solution interface structure was measured in deionized water (DIW) and 1 m RbCl + RbOH solution (pH 12) at 25 C with the X-ray crystal truncation rod method. The rutile surface in both solutions consists of a stoichiometric (1 1) surface unit mesh with the surface terminated by bridging oxygen (BO) and terminal oxygen (TO) sites. An additional hydration layer is observed above the TO site, with three distinct water adsorption sites each having well-defined vertical and lateral locations. Rb+ specifically adsorbs at the tetradentate site between the TO and BO sites, replacing one of the adsorbed water molecules at the interface. There is no further ordered water structure observed above the hydration layer. Structural displacements of atoms at the oxide surface are observed to be sensitive to the solution composition. Ti atom displacements from their bulk lattice positions, as large as 0.05 at the rutile (110)-DIW interface, decay in magnitude into the crystal with significant relaxations that are observable down to the fourth Ti-layer below the surface. A systematic outward shift was observed for Ti atom locations below the BO rows, while a systematic inward displacement was found for Ti atoms below the TO rows. Themore » Ti displacements were mostly reduced in contact with the RbCl solution at pH 12, with no statistically significant relaxations in the fourth layer Ti atoms. The distance between the surface 5-fold Ti atoms and the oxygen atoms of the TO site is 2.13 0.03 in DIW and 2.05 0.03 in the Rb+ solution, suggesting that water adsorbs mainly in molecular form to the rutile (110) surface at the TO site in DIW, while it is primarily in the form of an adsorbed hydroxyl group at pH 12.« less

Authors:
 [1];  [1];  [2];  [3];  [4];  [5]
  1. Argonne National Laboratory (ANL)
  2. University of Illinois, Chicago
  3. Northwestern University, Evanston
  4. Illinois State Water Survey, Champaign, IL
  5. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1081585
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Surface Science; Journal Volume: 601; Journal Issue: 4
Country of Publication:
United States
Language:
English

Citation Formats

Zhang, Zhan, Fenter, Paul, Sturchio, N. C., Bedzyk, Michael J., Machesky, Michael L., and Wesolowski, David J. Structure of Rutile TiO2 (110) in Water and 1 Molal Rb+ at pH 12: Interrelationship Among Surface Charge, Interfacial Hydration Structure, and Substrate Structural Displacements. United States: N. p., 2007. Web. doi:10.1016/j.susc.2006.12.007.
Zhang, Zhan, Fenter, Paul, Sturchio, N. C., Bedzyk, Michael J., Machesky, Michael L., & Wesolowski, David J. Structure of Rutile TiO2 (110) in Water and 1 Molal Rb+ at pH 12: Interrelationship Among Surface Charge, Interfacial Hydration Structure, and Substrate Structural Displacements. United States. doi:10.1016/j.susc.2006.12.007.
Zhang, Zhan, Fenter, Paul, Sturchio, N. C., Bedzyk, Michael J., Machesky, Michael L., and Wesolowski, David J. Mon . "Structure of Rutile TiO2 (110) in Water and 1 Molal Rb+ at pH 12: Interrelationship Among Surface Charge, Interfacial Hydration Structure, and Substrate Structural Displacements". United States. doi:10.1016/j.susc.2006.12.007.
@article{osti_1081585,
title = {Structure of Rutile TiO2 (110) in Water and 1 Molal Rb+ at pH 12: Interrelationship Among Surface Charge, Interfacial Hydration Structure, and Substrate Structural Displacements},
author = {Zhang, Zhan and Fenter, Paul and Sturchio, N. C. and Bedzyk, Michael J. and Machesky, Michael L. and Wesolowski, David J},
abstractNote = {The rutile (110)-aqueous solution interface structure was measured in deionized water (DIW) and 1 m RbCl + RbOH solution (pH 12) at 25 C with the X-ray crystal truncation rod method. The rutile surface in both solutions consists of a stoichiometric (1 1) surface unit mesh with the surface terminated by bridging oxygen (BO) and terminal oxygen (TO) sites. An additional hydration layer is observed above the TO site, with three distinct water adsorption sites each having well-defined vertical and lateral locations. Rb+ specifically adsorbs at the tetradentate site between the TO and BO sites, replacing one of the adsorbed water molecules at the interface. There is no further ordered water structure observed above the hydration layer. Structural displacements of atoms at the oxide surface are observed to be sensitive to the solution composition. Ti atom displacements from their bulk lattice positions, as large as 0.05 at the rutile (110)-DIW interface, decay in magnitude into the crystal with significant relaxations that are observable down to the fourth Ti-layer below the surface. A systematic outward shift was observed for Ti atom locations below the BO rows, while a systematic inward displacement was found for Ti atoms below the TO rows. The Ti displacements were mostly reduced in contact with the RbCl solution at pH 12, with no statistically significant relaxations in the fourth layer Ti atoms. The distance between the surface 5-fold Ti atoms and the oxygen atoms of the TO site is 2.13 0.03 in DIW and 2.05 0.03 in the Rb+ solution, suggesting that water adsorbs mainly in molecular form to the rutile (110) surface at the TO site in DIW, while it is primarily in the form of an adsorbed hydroxyl group at pH 12.},
doi = {10.1016/j.susc.2006.12.007},
journal = {Surface Science},
number = 4,
volume = 601,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}