Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms
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...
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2015
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219517_v322_n_p60_Mendive http://hdl.handle.net/20.500.12110/paper_00219517_v322_n_p60_Mendive |
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paper:paper_00219517_v322_n_p60_Mendive2023-06-08T14:43:39Z Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms Oxalic acid Photocatalysis Surface complexes Surface reactions Titanium dioxide Free radicals Molecules Organic acids Oxalic acid Oxide minerals Photocatalysis Photoreactivity Reaction intermediates Titanium dioxide Direct interactions Electron hole pairs Free radical species Intermediate formation Photocatalytic reactions Surface complex Surface reaction mechanism Theoretical calculations Surface reactions 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<inf>2</inf> 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<inf>2</inf> 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. © 2014 Elsevier Inc. All rights reserved. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219517_v322_n_p60_Mendive http://hdl.handle.net/20.500.12110/paper_00219517_v322_n_p60_Mendive |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Oxalic acid Photocatalysis Surface complexes Surface reactions Titanium dioxide Free radicals Molecules Organic acids Oxalic acid Oxide minerals Photocatalysis Photoreactivity Reaction intermediates Titanium dioxide Direct interactions Electron hole pairs Free radical species Intermediate formation Photocatalytic reactions Surface complex Surface reaction mechanism Theoretical calculations Surface reactions |
| spellingShingle |
Oxalic acid Photocatalysis Surface complexes Surface reactions Titanium dioxide Free radicals Molecules Organic acids Oxalic acid Oxide minerals Photocatalysis Photoreactivity Reaction intermediates Titanium dioxide Direct interactions Electron hole pairs Free radical species Intermediate formation Photocatalytic reactions Surface complex Surface reaction mechanism Theoretical calculations Surface reactions Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| topic_facet |
Oxalic acid Photocatalysis Surface complexes Surface reactions Titanium dioxide Free radicals Molecules Organic acids Oxalic acid Oxide minerals Photocatalysis Photoreactivity Reaction intermediates Titanium dioxide Direct interactions Electron hole pairs Free radical species Intermediate formation Photocatalytic reactions Surface complex Surface reaction mechanism Theoretical calculations Surface reactions |
| description |
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<inf>2</inf> 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<inf>2</inf> 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. © 2014 Elsevier Inc. All rights reserved. |
| title |
Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| title_short |
Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| title_full |
Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| title_fullStr |
Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| title_full_unstemmed |
Oxalic acid at the TiO<inf>2</inf>/water interface under UV(A) illumination: Surface reaction mechanisms |
| title_sort |
oxalic acid at the tio<inf>2</inf>/water interface under uv(a) illumination: surface reaction mechanisms |
| publishDate |
2015 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219517_v322_n_p60_Mendive http://hdl.handle.net/20.500.12110/paper_00219517_v322_n_p60_Mendive |
| _version_ |
1768542394088685568 |