Surface and electronic structure of titanium dioxide photocatalysts
TiO 2 films prepared by sol-gel route are active photocatalysts for the oxidation of organics in photoelectrochemical cells. The as-grown films for photocatalysis applications and those exposed to Ar + or H 2 + +Ar + ion bombardment are characterized by different spectroscopic methods, such as X-ray...
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2000
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Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15206106_v104_n42_p9851_Bilmes http://hdl.handle.net/20.500.12110/paper_15206106_v104_n42_p9851_Bilmes |
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paper:paper_15206106_v104_n42_p9851_Bilmes2023-06-08T16:18:51Z Surface and electronic structure of titanium dioxide photocatalysts Amorphous materials Atomic force microscopy Catalysts Charge transfer Electronic structure Gas adsorption Ion bombardment Optical films Photoelectrochemical cells Sol-gels Surface structure X ray diffraction analysis Nondissociative adsorption Photocatalysts Photothermal deflection spectroscopy (PDS) Titanium dioxide TiO 2 films prepared by sol-gel route are active photocatalysts for the oxidation of organics in photoelectrochemical cells. The as-grown films for photocatalysis applications and those exposed to Ar + or H 2 + +Ar + ion bombardment are characterized by different spectroscopic methods, such as X-ray diffraction (XRD), atomic force microscopy (AFM), UV-vis transmittance, photothermal deflection spectroscopy (PDS) and X-ray photoelectron spectroscopy (XPS), as well as by conductance. This material has defects associated with oxygen vacancies produced during the sample preparation which support nondissociative adsorption of O 2 when films are exposed to air. Charge transfer from reduced Ti species to adsorbed dioxygen leads to Ti-O 2 - surface complexes that are partially removed by heating at 200 °C, and fully removed after 30 min ion bombardment. By comparison with the relatively well-understood structural defects of bombarded TiO 2 we arise to a quite complete structural model of the as grown material which corresponds to an amorphous semiconductor possessing relative low disorder and density of states as compared with a pure amorphous material. These TiO 2 films are modeled as low size crystalline domain embedded in an amorphous matrix whose electronic structure exhibit exponential band tails and a narrow band close to the conduction band. The latter is fully or partially occupied depending on the presence of adsorbed electron scavengers such as dioxygen. © 2000 American Chemical Society. 2000 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15206106_v104_n42_p9851_Bilmes http://hdl.handle.net/20.500.12110/paper_15206106_v104_n42_p9851_Bilmes |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
Amorphous materials Atomic force microscopy Catalysts Charge transfer Electronic structure Gas adsorption Ion bombardment Optical films Photoelectrochemical cells Sol-gels Surface structure X ray diffraction analysis Nondissociative adsorption Photocatalysts Photothermal deflection spectroscopy (PDS) Titanium dioxide |
spellingShingle |
Amorphous materials Atomic force microscopy Catalysts Charge transfer Electronic structure Gas adsorption Ion bombardment Optical films Photoelectrochemical cells Sol-gels Surface structure X ray diffraction analysis Nondissociative adsorption Photocatalysts Photothermal deflection spectroscopy (PDS) Titanium dioxide Surface and electronic structure of titanium dioxide photocatalysts |
topic_facet |
Amorphous materials Atomic force microscopy Catalysts Charge transfer Electronic structure Gas adsorption Ion bombardment Optical films Photoelectrochemical cells Sol-gels Surface structure X ray diffraction analysis Nondissociative adsorption Photocatalysts Photothermal deflection spectroscopy (PDS) Titanium dioxide |
description |
TiO 2 films prepared by sol-gel route are active photocatalysts for the oxidation of organics in photoelectrochemical cells. The as-grown films for photocatalysis applications and those exposed to Ar + or H 2 + +Ar + ion bombardment are characterized by different spectroscopic methods, such as X-ray diffraction (XRD), atomic force microscopy (AFM), UV-vis transmittance, photothermal deflection spectroscopy (PDS) and X-ray photoelectron spectroscopy (XPS), as well as by conductance. This material has defects associated with oxygen vacancies produced during the sample preparation which support nondissociative adsorption of O 2 when films are exposed to air. Charge transfer from reduced Ti species to adsorbed dioxygen leads to Ti-O 2 - surface complexes that are partially removed by heating at 200 °C, and fully removed after 30 min ion bombardment. By comparison with the relatively well-understood structural defects of bombarded TiO 2 we arise to a quite complete structural model of the as grown material which corresponds to an amorphous semiconductor possessing relative low disorder and density of states as compared with a pure amorphous material. These TiO 2 films are modeled as low size crystalline domain embedded in an amorphous matrix whose electronic structure exhibit exponential band tails and a narrow band close to the conduction band. The latter is fully or partially occupied depending on the presence of adsorbed electron scavengers such as dioxygen. © 2000 American Chemical Society. |
title |
Surface and electronic structure of titanium dioxide photocatalysts |
title_short |
Surface and electronic structure of titanium dioxide photocatalysts |
title_full |
Surface and electronic structure of titanium dioxide photocatalysts |
title_fullStr |
Surface and electronic structure of titanium dioxide photocatalysts |
title_full_unstemmed |
Surface and electronic structure of titanium dioxide photocatalysts |
title_sort |
surface and electronic structure of titanium dioxide photocatalysts |
publishDate |
2000 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15206106_v104_n42_p9851_Bilmes http://hdl.handle.net/20.500.12110/paper_15206106_v104_n42_p9851_Bilmes |
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1768546459990360064 |