Chemical Reactivity of Reduced TiO2(110): The dominant role of surface defects in oxygen chemisorption
O2 chemisorption on reduced, rutile TiO2(110) with various concentrations of oxygen vacancies (Ov) and bridging hydroxyls (OHb) is investigated with scanning tunneling microscopy, temperature programmed desorption and electron-stimulated desorption. On the annealed surface, 2 oxygen molecules can be chemisorbed per Ov. The same amount of O2 chemisorbs on surfaces where each Ov is converted to two OHb’s by exposure to water (i.e. 1 O2 per OHb). Surfaces with few or no Ov’s or OHb’s can be created by exposing the hydroxylated surface to O2 at room temperature, and the amount of O2 that chemisorbs on these surfaces at low temperatures is only ~20% of the amount on the annealed (reduced) surface. In contrast, the amount of chemisorbed O2 increases by more than a factor of two when the OHb concentration is enhanced – without changing the concentration of sub-surface Ti interstitials. The results indicate that the reactivity of TiO2(110) is primarily controlled by the amount of electron-donating surface species such as Ov’s and/or OHb’s, and not Ti3+ interstitials.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 963828
- Report Number(s):
- PNNL-SA-65119; 25619; 24800; 24799; KC0301010
- Journal Information:
- Journal of Physical Chemistry C, 113(28):12407-12411, Journal Name: Journal of Physical Chemistry C, 113(28):12407-12411 Journal Issue: 28 Vol. 113; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrogen Reactivity on Highly-hydroxylated TiO2(110) Surfaces Prepared via Carboxylic Acid Adsorption and Photolysis
Insights into Photoexcited Electron Scavenging Processes on TiO2 Obtained from Studies of the Reaction of O2 with OH Groups Adsorbed at Electronic Defects on TiO2 (110)