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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todo:paper_15206106_v104_n42_p9851_Bilmes2023-10-03T16:20:04Z Surface and electronic structure of titanium dioxide photocatalysts Bilmes, S.A. Mandelbaum, P. Alvarez, F. Victoria, N.M. 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. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_15206106_v104_n42_p9851_Bilmes |
| institution |
Universidad de Buenos Aires |
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I-28 |
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R-134 |
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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 Bilmes, S.A. Mandelbaum, P. Alvarez, F. Victoria, N.M. 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. |
| format |
JOUR |
| author |
Bilmes, S.A. Mandelbaum, P. Alvarez, F. Victoria, N.M. |
| author_facet |
Bilmes, S.A. Mandelbaum, P. Alvarez, F. Victoria, N.M. |
| author_sort |
Bilmes, S.A. |
| 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 |
| url |
http://hdl.handle.net/20.500.12110/paper_15206106_v104_n42_p9851_Bilmes |
| work_keys_str_mv |
AT bilmessa surfaceandelectronicstructureoftitaniumdioxidephotocatalysts AT mandelbaump surfaceandelectronicstructureoftitaniumdioxidephotocatalysts AT alvarezf surfaceandelectronicstructureoftitaniumdioxidephotocatalysts AT victorianm surfaceandelectronicstructureoftitaniumdioxidephotocatalysts |
| _version_ |
1782030486031302656 |