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XPS characterization of Au/TiO2 catalysts: Binding energy assessment and irradiation effects

Paper ID Volume ID Publish Year Pages File Format Full-Text
41658 45895 2011 10 PDF Available
Title
XPS characterization of Au/TiO2 catalysts: Binding energy assessment and irradiation effects
Abstract

X-ray photoelectron spectroscopy (XPS) was employed to study the surface composition and electronic structure of Au/TiO2 catalysts in comparison with TiO2 (anatase) and to reveal time-dependent X-ray irradiation damage of the samples. The occurrence of Au nano-sized particles on a TiO2 support was found to result in a slight shift of Ti 2p core-level spectrum and in changes of the valence band and X-ray induced Auger spectra, compared to TiO2-only. It was shown that for different means of energy referencing the charge-corrected Au 4f7/2 binding energy in Au/TiO2 catalysts was 0.15–0.45 eV lower than that in pure bulk Au. Exposure to X-rays of Au/TiO2 catalysts and pure TiO2 caused a reduction of Ti 4+ oxidation state and desorption of oxygen from the surface. As a result, the surface chemical composition and electronic structure of the samples changed with time. The X-ray irradiation affected charge transfer processes in Au/TiO2 so that the pattern of X-ray induced damage in the Au-based catalyst turned out to be quite different from that in TiO2, with some characteristics displaying the very opposite features. Decreasing of the Au 4f7/2 binding energy and concurrent increasing of the fraction of Ti3+ species observed in the beginning of X-ray irradiation of Au/TiO2 may be taken as direct evidence for charge transfer from oxygen vacancies created by irradiation to Au particles.

Graphical abstractA comparative XPS study of the surface composition and electronic structure of Au/TiO2 catalysts and TiO2 (anatase) was carried out and time-dependent X-ray irradiation damage of the samples was examined. In Au/TiO2, charge transfer processes triggered by X-ray irradiation were found to develop which caused the variation of core-level binding energies.Figure optionsDownload full-size imageDownload high-quality image (35 K)Download as PowerPoint slide

Keywords
Au/TiO2 catalyst; TiO2; XPS; X-ray induced damage; Valence band
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XPS characterization of Au/TiO2 catalysts: Binding energy assessment and irradiation effects
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 391, Issues 1–2, 4 January 2011, Pages 367–376
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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Full-text PDF Download
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