Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 60-72 |
| Seitenumfang | 13 |
| Fachzeitschrift | Journal of catalysis |
| Jahrgang | 322 |
| Publikationsstatus | Veröffentlicht - Feb. 2015 |
Abstract
It is through the comparison of experimental results and theoretical calculations that the mechanistic details of several surface photoreactions initiated upon UV(A) illumination of adsorbed oxalic acid on rutile and anatase can be proposed. The absorption of light is found to be rather localized at surface Ti atoms and at the adsorbed species on both TiO 2 polymorphs, respectively. Different surface complexes exhibit different photoreactivities, and consequently, each of them may follow a different reaction mechanism. Experimental data can be explained involving reactions such as the interconversion of monodentate into bidentate species which may further be oxidized to CO 2 or may even produce OH radicals, while the reduction of monodentate species to the respective aldehyde results in combination with the oxidation of a neighbouring adsorbed OH group into the formation of an adsorbed OOH radical. On the basis of the results presented herein, it is concluded that the direct action of the photocatalytically produced electron-hole pairs on the adsorbed species is the primary step of the photocatalytic reaction, while the intermediate formation of free radical species followed by their reaction with an oxalate molecule can be regarded as a secondary process. Within the system described in this work, OH radicals only appear to be produced following the direct interaction of a hole with the adsorbed organic compound, but not with chemisorbed water molecules.
ASJC Scopus Sachgebiete
- Chemische Verfahrenstechnik (insg.)
- Katalyse
- Chemie (insg.)
- Physikalische und Theoretische Chemie
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in: Journal of catalysis, Jahrgang 322, 02.2015, S. 60-72.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Oxalic acid at the TiO2/water interface under UV(A) illumination
T2 - Surface reaction mechanisms
AU - Mendive, C.B.
AU - Bredow, T.
AU - Schneider, J.
AU - Blesa, M.
AU - Bahnemann, D.
N1 - Funding information: We gratefully acknowledge the financial support by Agencia Nacional de Promoción Científica y Tecnológica (ANPCYT), Argentina (project PICT-2683); and by Millennium Inorganic Chemicals (now CRISTAL GLOBAL). We want to thank MINCyT (Argentina) and BMBF (Germany) for the financial support of the exchange project AL1209. CBM is a member of the research staff of CONICET. JS gratefully acknowledges financial support from the German Ministry of Science and Technology (BMBF), Grant Number 033RC1012C (Neue Katalysatoren und Technologien für die solarchemische Wasserstofferzeugung, HyCats). TB gratefully acknowledges the financial support by Deutsche Forschungsgemeinschaft within the Collaborate Research Center SFB 813 Chemistry at Spin Centers.
PY - 2015/2
Y1 - 2015/2
N2 - It is through the comparison of experimental results and theoretical calculations that the mechanistic details of several surface photoreactions initiated upon UV(A) illumination of adsorbed oxalic acid on rutile and anatase can be proposed. The absorption of light is found to be rather localized at surface Ti atoms and at the adsorbed species on both TiO 2 polymorphs, respectively. Different surface complexes exhibit different photoreactivities, and consequently, each of them may follow a different reaction mechanism. Experimental data can be explained involving reactions such as the interconversion of monodentate into bidentate species which may further be oxidized to CO 2 or may even produce OH radicals, while the reduction of monodentate species to the respective aldehyde results in combination with the oxidation of a neighbouring adsorbed OH group into the formation of an adsorbed OOH radical. On the basis of the results presented herein, it is concluded that the direct action of the photocatalytically produced electron-hole pairs on the adsorbed species is the primary step of the photocatalytic reaction, while the intermediate formation of free radical species followed by their reaction with an oxalate molecule can be regarded as a secondary process. Within the system described in this work, OH radicals only appear to be produced following the direct interaction of a hole with the adsorbed organic compound, but not with chemisorbed water molecules.
AB - It is through the comparison of experimental results and theoretical calculations that the mechanistic details of several surface photoreactions initiated upon UV(A) illumination of adsorbed oxalic acid on rutile and anatase can be proposed. The absorption of light is found to be rather localized at surface Ti atoms and at the adsorbed species on both TiO 2 polymorphs, respectively. Different surface complexes exhibit different photoreactivities, and consequently, each of them may follow a different reaction mechanism. Experimental data can be explained involving reactions such as the interconversion of monodentate into bidentate species which may further be oxidized to CO 2 or may even produce OH radicals, while the reduction of monodentate species to the respective aldehyde results in combination with the oxidation of a neighbouring adsorbed OH group into the formation of an adsorbed OOH radical. On the basis of the results presented herein, it is concluded that the direct action of the photocatalytically produced electron-hole pairs on the adsorbed species is the primary step of the photocatalytic reaction, while the intermediate formation of free radical species followed by their reaction with an oxalate molecule can be regarded as a secondary process. Within the system described in this work, OH radicals only appear to be produced following the direct interaction of a hole with the adsorbed organic compound, but not with chemisorbed water molecules.
KW - Oxalic acid
KW - Photocatalysis
KW - Surface complexes
KW - Surface reactions
KW - Titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=84941619520&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2014.11.008
DO - 10.1016/j.jcat.2014.11.008
M3 - Article
VL - 322
SP - 60
EP - 72
JO - Journal of catalysis
JF - Journal of catalysis
SN - 0021-9517
ER -