The adsorption of liquid and vapor water on TiO{sub 2}(110) surfaces: The role of defects

Conference · Fri Sep 01 04:00:00 EDT 1995

OSTI ID:94040

Wang, L Q; Baer, D R; Engelhard, M H ^[1]

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1. Pacific Northwest Lab., Richland, WA (United States)

The adsorption of liquid and vapor water on defective and nearly defect-free TiO{sub 2}(110) surfaces has been examined using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). The study has focused on examining electronic defects as created in vacuum and after exposure to both liquid and vapor water. The defective surfaces were prepared by electron-beam exposure and Ar{sup +} bombardment. With exposure up to 10{sup 4}L low vapor pressure (<10{sup {minus}5}Torr) water to defective surfaces, little or not changes on Ti 3d defect intensities were observed, in agreement with the previous studies. However, defect intensities were greatly reduced after exposing defective surfaces to {approximately} 10{sup 8}L higher vapor pressure (0.2--0.6 Torr) water for 5 min. More significantly, XPS and UPS spectra showed that electron-beam induced defects were completely removed upon liquid water exposure, while defects created by Ar{sup +} bombardment were only partially removed. It was found that surface defects created by Ar{sup +} bombardment were removed more readily than sub-surface defects. For a nearly defect-free surface, water coverages were {approximately} 0.02 ML at 10{sup 4}L exposure to low vapor pressure water, {approximately} 0.07 ML at 10{sup 8}L exposure to higher vapor pressure water, and {approximately} 0.125 ML with liquid water exposure, respectively.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 94040
• Report Number(s): CONF-941144--; ISBN 1-55899-258-8
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
BINDING ENERGY
ELECTRONIC STRUCTURE
EMISSION SPECTROSCOPY
PHOTOELECTRON SPECTROSCOPY
SORPTIVE PROPERTIES
SURFACES
TITANIUM OXIDES
ULTRAHIGH VACUUM
ULTRAVIOLET SPECTRA
WATER
WATER VAPOR
X-RAY SPECTROSCOPY