Creating Excess Electrons at the Anatase TiO2(101) Surface

Excess electrons facilitate redox reactions at the technologically relevant anatase TiO 2 (101) surface. The availability of these electrons is related to the defect concentration at the surface. We present two-photon (2PPE, 3.10–3.54 eV) and ultraviolet (UPS, 21.2 & 40.8 eV) photoemission spect...

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Bibliographic Details
Published in:Topics in catalysis 2017, Vol.60 (6-7), p.392-400
Main Authors: Payne, D. T., Zhang, Y., Pang, C. L., Fielding, H. H., Thornton, G.
Format: Article
Language:English
Subjects:
Anatase
Balancing
Catalysis
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Electron bombardment
Fermi level
Industrial Chemistry/Chemical Engineering
Irradiation
Molecular orbitals
Original Paper
Oxygen
Pharmacy
Photoelectric emission
Photoelectron spectroscopy
Physical Chemistry
Redox reactions
Spectra
Spectroscopic analysis
Spectrum analysis
Titanium dioxide
Titanium oxides
Ultraviolet
Vacancies
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Summary:Excess electrons facilitate redox reactions at the technologically relevant anatase TiO 2 (101) surface. The availability of these electrons is related to the defect concentration at the surface. We present two-photon (2PPE, 3.10–3.54 eV) and ultraviolet (UPS, 21.2 & 40.8 eV) photoemission spectroscopy measurements evidencing an increased concentration of excess electrons following electron bombardment at room temperature. Irradiation-induced surface oxygen vacancies are known to migrate into the sub-surface at this temperature, quickly equilibrating the surface defect concentration. Hence, we propose that the irradiated surface is hydroxylated. Peaks in UPS difference spectra are observed centred 8.45, 6.50 and 0.73 eV below the Fermi level, which are associated with the 3σ and 1π hydroxyl molecular orbitals and Ti 3d band gap states, respectively. The higher concentration of excess electrons at the hydroxylated anatase (101) surface may increase the potential for redox reactions.
ISSN:1022-5528
1572-9028
DOI:10.1007/s11244-016-0706-8