Details
| Original language | English |
|---|---|
| Pages (from-to) | 902-910 |
| Number of pages | 9 |
| Journal | Catalysis Science and Technology |
| Volume | 7 |
| Issue number | 4 |
| Publication status | Published - 21 Feb 2017 |
Abstract
Experiments of photocatalytic oxidation of H 2 16O with a suspended oxygen-isotope labelled Ti 18O 2 photocatalyst are presented here for the first time. The photo-induced evolution of 18O 16O demonstrates that bridging surface oxygens (> 18O br 2-) behave as real catalytic species of the global water splitting photocatalytic reaction (2H 2O + 4h + → O 2(g)↑ + 4H +). The experimental results are interpreted according to a previously developed water redox photooxidation (WRP) mechanism (Salvador, P. Prog. Surf. Sci. 2011, 86, 41-58), opening a new mechanistic pathway that involves the participation of terminal >O br 2- bridging oxygens as real photocatalytic species. In the primary step, one-fold coordinated - 18O br - radicals are generated from the direct photooxidation of > 18O br 2- oxygens with valence band holes (> 18O br 2- + h + → - 18O br -). In the second step, a couple of adjacent - 18O br - radicals chemically react, giving rise to peroxo species (2 18O br - → 18O 2 2-), which are further photooxidized with photogenerated valence band holes, initially leading to 18O 2(g) evolution according to the global photoreaction 18O 2 2- + 4h + → 2V[> 18O br 2-] + 18O 2(g)↑. Terminal oxygen vacancies (V[> 18O br 2-]) become further healed via dissociative adsorption of H 2 16O water molecules (2V[> 18O br 2-] + 2H 2 16O → 2(> 16O br 2-) + 2H +), in such a way that > 18O br 2- bridging ions are progressively substituted by > 16O br 2- and the initially evolved 18O 2(g) is further replaced by 16,18O 2(g) and finally by 16O 2(g).
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In: Catalysis Science and Technology, Vol. 7, No. 4, 21.02.2017, p. 902-910.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Catalytic role of bridging oxygens in TiO2 liquid phase photocatalytic reactions
T2 - Analysis of H216O photooxidation on labeled Ti18O2
AU - Montoya, J.F.
AU - Bahnemann, D.W.
AU - Salvador, P.
AU - Peral, J.
N1 - Publisher Copyright: © 2017 The Royal Society of Chemistry. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/2/21
Y1 - 2017/2/21
N2 - Experiments of photocatalytic oxidation of H 2 16O with a suspended oxygen-isotope labelled Ti 18O 2 photocatalyst are presented here for the first time. The photo-induced evolution of 18O 16O demonstrates that bridging surface oxygens (> 18O br 2-) behave as real catalytic species of the global water splitting photocatalytic reaction (2H 2O + 4h + → O 2(g)↑ + 4H +). The experimental results are interpreted according to a previously developed water redox photooxidation (WRP) mechanism (Salvador, P. Prog. Surf. Sci. 2011, 86, 41-58), opening a new mechanistic pathway that involves the participation of terminal >O br 2- bridging oxygens as real photocatalytic species. In the primary step, one-fold coordinated - 18O br - radicals are generated from the direct photooxidation of > 18O br 2- oxygens with valence band holes (> 18O br 2- + h + → - 18O br -). In the second step, a couple of adjacent - 18O br - radicals chemically react, giving rise to peroxo species (2 18O br - → 18O 2 2-), which are further photooxidized with photogenerated valence band holes, initially leading to 18O 2(g) evolution according to the global photoreaction 18O 2 2- + 4h + → 2V[> 18O br 2-] + 18O 2(g)↑. Terminal oxygen vacancies (V[> 18O br 2-]) become further healed via dissociative adsorption of H 2 16O water molecules (2V[> 18O br 2-] + 2H 2 16O → 2(> 16O br 2-) + 2H +), in such a way that > 18O br 2- bridging ions are progressively substituted by > 16O br 2- and the initially evolved 18O 2(g) is further replaced by 16,18O 2(g) and finally by 16O 2(g).
AB - Experiments of photocatalytic oxidation of H 2 16O with a suspended oxygen-isotope labelled Ti 18O 2 photocatalyst are presented here for the first time. The photo-induced evolution of 18O 16O demonstrates that bridging surface oxygens (> 18O br 2-) behave as real catalytic species of the global water splitting photocatalytic reaction (2H 2O + 4h + → O 2(g)↑ + 4H +). The experimental results are interpreted according to a previously developed water redox photooxidation (WRP) mechanism (Salvador, P. Prog. Surf. Sci. 2011, 86, 41-58), opening a new mechanistic pathway that involves the participation of terminal >O br 2- bridging oxygens as real photocatalytic species. In the primary step, one-fold coordinated - 18O br - radicals are generated from the direct photooxidation of > 18O br 2- oxygens with valence band holes (> 18O br 2- + h + → - 18O br -). In the second step, a couple of adjacent - 18O br - radicals chemically react, giving rise to peroxo species (2 18O br - → 18O 2 2-), which are further photooxidized with photogenerated valence band holes, initially leading to 18O 2(g) evolution according to the global photoreaction 18O 2 2- + 4h + → 2V[> 18O br 2-] + 18O 2(g)↑. Terminal oxygen vacancies (V[> 18O br 2-]) become further healed via dissociative adsorption of H 2 16O water molecules (2V[> 18O br 2-] + 2H 2 16O → 2(> 16O br 2-) + 2H +), in such a way that > 18O br 2- bridging ions are progressively substituted by > 16O br 2- and the initially evolved 18O 2(g) is further replaced by 16,18O 2(g) and finally by 16O 2(g).
UR - http://www.scopus.com/inward/record.url?scp=85021719973&partnerID=8YFLogxK
U2 - 10.1039/c6cy02457b
DO - 10.1039/c6cy02457b
M3 - Article
VL - 7
SP - 902
EP - 910
JO - Catalysis Science and Technology
JF - Catalysis Science and Technology
SN - 2044-4753
IS - 4
ER -