Electron traps and their effect on the surface chemistry of TiO2 (110)

Papageorgiou, Anthoula C, Beglitis, Nicholaos S, Pang, Chi L, Gregory, Teobaldi, Chen, Qiao, Fisher, Andrew J, Hofer, Werner A and Thornton, Geoff (2010) Electron traps and their effect on the surface chemistry of TiO2 (110). Proceedings of the National Academy of Sciences, 107 (6). pp. 2391-2396. ISSN 0027-8424

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Abstract

Oxygen vacancies on metal oxide surfaces have long been thought to play a key role in the surface chemistry. Such processes have been directly visualized in the case of the model photocatalyst surface TiO2 (110) in reactions with water and molecular oxygen. These vacancies have been assumed to be neutral in calculations of the surface properties. However, by comparing experimental and simulated scanning tunneling microscopy images and spectra, we show that oxygen vacancies act as trapping centers and are negatively charged. We demonstrate that charging the defect significantly affects the reactivity by following the reaction of molecular oxygen with surface hydroxyl formed by water dissociation at the vacancies. Calculations with electronically charged hydroxyl favor a condensation reaction forming water and surface oxygen adatoms, in line with experimental observations. This contrasts with simulations using neutral hydroxyl where hydrogen peroxide is found to be the most stable product.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Subjects: Q Science
Depositing User: Qiao Chen
Date Deposited: 06 Feb 2012 18:39
Last Modified: 04 Oct 2012 14:36
URI: http://sro.sussex.ac.uk/id/eprint/17618
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