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Creating Excess Electrons at the Anatase TiO2(101) Surface
D T Payne1,2, Y Zhang1,2, C L Pang1,2
11Department of Chemistry, University College London, London, WC1H 0AJ UK.
Topics in Catalysis
|February 7, 2020
Summary
Electron bombardment increases excess electrons on the anatase titanium dioxide (TiO2) surface, enhancing its potential for redox reactions. This study links surface defects to increased electron concentration and proposes a hydroxylated surface structure.
Area of Science:
- Materials Science
- Surface Chemistry
- Physical Chemistry
Background:
- Excess electrons on anatase TiO2(101) surfaces are crucial for redox reactions.
- Surface defect concentration directly influences electron availability.
Purpose of the Study:
- To investigate the effect of electron bombardment on excess electron concentration at the anatase TiO2(101) surface.
- To elucidate the surface species and defect structures responsible for changes in electron concentration.
Main Methods:
- Two-photon photoemission spectroscopy (2PPE) with photon energies of 3.10–3.54 eV.
- Ultraviolet photoemission spectroscopy (UPS) with photon energies of 21.2 and 40.8 eV.
- Analysis of surface defect dynamics and electronic states.
Main Results:
- Electron bombardment at room temperature significantly increased excess electron concentration.
- Observed UPS spectral features at 8.45 eV, 6.50 eV, and 0.73 eV below the Fermi level.
- These features are attributed to hydroxyl molecular orbitals and Ti 3d band gap states, suggesting surface hydroxylation.
Conclusions:
- Electron bombardment leads to a hydroxylated anatase TiO2(101) surface with a higher concentration of excess electrons.
- This increased electron density enhances the surface's potential for catalytic redox reactions.
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