Details
| Original language | English |
|---|---|
| Pages (from-to) | 2311-2320 |
| Number of pages | 10 |
| Journal | CHEMPHYSCHEM |
| Volume | 15 |
| Issue number | 11 |
| Early online date | 14 May 2014 |
| Publication status | Published - 4 Aug 2014 |
Abstract
On the basis of experiments carried out with controlled amounts of residual oxygen and water, or by using oxygen-isotope-labeled Ti 18O 2 as the photocatalyst, we demonstrate that 18O s atoms behave as real catalytic species in the photo-oxidation of acetonitrile-dissolved aromatic compounds such as benzene, phenol, and benzaldehyde with TiO 2. The experimental evidence allows a terminal-oxygen indirect electron-transfer (TOIET) mechanism to be proposed, which is a new pathway that involves the trapping of free photogenerated valence-band holes at O s species and their incorporation into the reaction products, with simultaneous generation of oxygen vacancies at the TiO 2 surface and their subsequent healing with oxygen atoms from either O 2 or H 2O molecules that are dissolved in the liquid phase. According to the TOIET mechanism, the TiO 2 surface is not considered to remain stable, but is continuously changing in the course of the photocatalytic reaction, challenging earlier interpretations of TiO 2 photocatalytic phenomena. A stable surface? TiO 2- assisted photocatalytic oxidation of organic compounds involves the exchange of surface oxygen on the catalyst, the generation of a surface oxygen vacancy, and the final incorporation of a water molecule to heal the vacancy.
Keywords
- isotopic labeling, oxidation, photophysics, reaction mechanisms, surface chemistry
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Atomic and Molecular Physics, and Optics
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: CHEMPHYSCHEM, Vol. 15, No. 11, 04.08.2014, p. 2311-2320.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Catalytic role of TiO2 terminal oxygen atoms in liquid-phase photocatalytic reactions
T2 - Oxidation of aromatic compounds in anhydrous acetonitrile
AU - Montoya, J.F.
AU - Bahnemann, D.W.
AU - Peral, J.
AU - Salvador, P.
N1 - Copyright: Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/8/4
Y1 - 2014/8/4
N2 - On the basis of experiments carried out with controlled amounts of residual oxygen and water, or by using oxygen-isotope-labeled Ti 18O 2 as the photocatalyst, we demonstrate that 18O s atoms behave as real catalytic species in the photo-oxidation of acetonitrile-dissolved aromatic compounds such as benzene, phenol, and benzaldehyde with TiO 2. The experimental evidence allows a terminal-oxygen indirect electron-transfer (TOIET) mechanism to be proposed, which is a new pathway that involves the trapping of free photogenerated valence-band holes at O s species and their incorporation into the reaction products, with simultaneous generation of oxygen vacancies at the TiO 2 surface and their subsequent healing with oxygen atoms from either O 2 or H 2O molecules that are dissolved in the liquid phase. According to the TOIET mechanism, the TiO 2 surface is not considered to remain stable, but is continuously changing in the course of the photocatalytic reaction, challenging earlier interpretations of TiO 2 photocatalytic phenomena. A stable surface? TiO 2- assisted photocatalytic oxidation of organic compounds involves the exchange of surface oxygen on the catalyst, the generation of a surface oxygen vacancy, and the final incorporation of a water molecule to heal the vacancy.
AB - On the basis of experiments carried out with controlled amounts of residual oxygen and water, or by using oxygen-isotope-labeled Ti 18O 2 as the photocatalyst, we demonstrate that 18O s atoms behave as real catalytic species in the photo-oxidation of acetonitrile-dissolved aromatic compounds such as benzene, phenol, and benzaldehyde with TiO 2. The experimental evidence allows a terminal-oxygen indirect electron-transfer (TOIET) mechanism to be proposed, which is a new pathway that involves the trapping of free photogenerated valence-band holes at O s species and their incorporation into the reaction products, with simultaneous generation of oxygen vacancies at the TiO 2 surface and their subsequent healing with oxygen atoms from either O 2 or H 2O molecules that are dissolved in the liquid phase. According to the TOIET mechanism, the TiO 2 surface is not considered to remain stable, but is continuously changing in the course of the photocatalytic reaction, challenging earlier interpretations of TiO 2 photocatalytic phenomena. A stable surface? TiO 2- assisted photocatalytic oxidation of organic compounds involves the exchange of surface oxygen on the catalyst, the generation of a surface oxygen vacancy, and the final incorporation of a water molecule to heal the vacancy.
KW - isotopic labeling
KW - oxidation
KW - photophysics
KW - reaction mechanisms
KW - surface chemistry
UR - http://www.scopus.com/inward/record.url?scp=84904878800&partnerID=8YFLogxK
U2 - 10.1002/cphc.201402043
DO - 10.1002/cphc.201402043
M3 - Article
VL - 15
SP - 2311
EP - 2320
JO - CHEMPHYSCHEM
JF - CHEMPHYSCHEM
SN - 1439-4235
IS - 11
ER -