Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system
Similarly to alizarin molecules, 3,4-dihydroxy-9,10-dioxo-2- anthracenesulfonate (alizarin red, AR), chelates TiO2 nanoparticles through the catechol moiety, and shifts the absorption threshold of the semiconductor to the visible region. The photoinduced reactivity of the coupled system AR@TiO2 was...
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2008
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paper:paper_19327447_v112_n42_p16532_DiIorio2023-06-08T16:31:27Z Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system Litter, Marta Irene Argon Chemisorption Chromium Colloids Electrolytic reduction Electron spin resonance spectroscopy Irradiation Ligands Nanoparticles Nanostructured materials Nanostructures Oxygen Paramagnetic resonance Paramagnetism Photodegradation Quantum efficiency System stability Vegetation Constrained environments Coupled systems Electron paramagnetic resonance spectroscopies Environmental implications High stabilities Nanoparticulate systems Oxygen reductions Photo induced Photogenerated electrons Semi-conductors Spectroscopic evidences Visible irradiations Visible lights Visible regions Chromium compounds Similarly to alizarin molecules, 3,4-dihydroxy-9,10-dioxo-2- anthracenesulfonate (alizarin red, AR), chelates TiO2 nanoparticles through the catechol moiety, and shifts the absorption threshold of the semiconductor to the visible region. The photoinduced reactivity of the coupled system AR@TiO2 was investigated through quantum yields determinations in nonscattering sols of TiO2 modified nanoparticles. In contrast with the behavior observed in TiO2 microparticulated systems, the chemisorbed ligand has a high stability under aerated visible light irradiation. The quantum yield for alizarin red oxidation Φ-AR = 4 × 10-4 correlates with the negligible efficiency for oxygen reduction in the constrained environment of the smaller particles, Conversely, reduction of Cr(VI) to Cr(V) in the coupled AR@TiO2 system, confirmed by electron paramagnetic resonance spectroscopy, utilizes a high fraction of the photogenerated electrons and induces the degradation of the complex. Quantum efficiencies for chromium(VI) disappearance, Φ-cr(v1). approaches 37% at [Cr(VI)]0 = 200 μM. The interactions between Cr(VI)/AR and Cr(VI)/TiO2 are analyzed in detail. Spectroscopic evidence is presented for the first time that Cr(VI) forms a charge-transfer complex with TiO2 nanoparticles that could be excited by visible light (λ < 440 nm). The environmental implications of the above findings are briefly discussed. © 2008 American Chemical Society. Fil:Litter, M.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2008 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_19327447_v112_n42_p16532_DiIorio http://hdl.handle.net/20.500.12110/paper_19327447_v112_n42_p16532_DiIorio |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Argon Chemisorption Chromium Colloids Electrolytic reduction Electron spin resonance spectroscopy Irradiation Ligands Nanoparticles Nanostructured materials Nanostructures Oxygen Paramagnetic resonance Paramagnetism Photodegradation Quantum efficiency System stability Vegetation Constrained environments Coupled systems Electron paramagnetic resonance spectroscopies Environmental implications High stabilities Nanoparticulate systems Oxygen reductions Photo induced Photogenerated electrons Semi-conductors Spectroscopic evidences Visible irradiations Visible lights Visible regions Chromium compounds |
| spellingShingle |
Argon Chemisorption Chromium Colloids Electrolytic reduction Electron spin resonance spectroscopy Irradiation Ligands Nanoparticles Nanostructured materials Nanostructures Oxygen Paramagnetic resonance Paramagnetism Photodegradation Quantum efficiency System stability Vegetation Constrained environments Coupled systems Electron paramagnetic resonance spectroscopies Environmental implications High stabilities Nanoparticulate systems Oxygen reductions Photo induced Photogenerated electrons Semi-conductors Spectroscopic evidences Visible irradiations Visible lights Visible regions Chromium compounds Litter, Marta Irene Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| topic_facet |
Argon Chemisorption Chromium Colloids Electrolytic reduction Electron spin resonance spectroscopy Irradiation Ligands Nanoparticles Nanostructured materials Nanostructures Oxygen Paramagnetic resonance Paramagnetism Photodegradation Quantum efficiency System stability Vegetation Constrained environments Coupled systems Electron paramagnetic resonance spectroscopies Environmental implications High stabilities Nanoparticulate systems Oxygen reductions Photo induced Photogenerated electrons Semi-conductors Spectroscopic evidences Visible irradiations Visible lights Visible regions Chromium compounds |
| description |
Similarly to alizarin molecules, 3,4-dihydroxy-9,10-dioxo-2- anthracenesulfonate (alizarin red, AR), chelates TiO2 nanoparticles through the catechol moiety, and shifts the absorption threshold of the semiconductor to the visible region. The photoinduced reactivity of the coupled system AR@TiO2 was investigated through quantum yields determinations in nonscattering sols of TiO2 modified nanoparticles. In contrast with the behavior observed in TiO2 microparticulated systems, the chemisorbed ligand has a high stability under aerated visible light irradiation. The quantum yield for alizarin red oxidation Φ-AR = 4 × 10-4 correlates with the negligible efficiency for oxygen reduction in the constrained environment of the smaller particles, Conversely, reduction of Cr(VI) to Cr(V) in the coupled AR@TiO2 system, confirmed by electron paramagnetic resonance spectroscopy, utilizes a high fraction of the photogenerated electrons and induces the degradation of the complex. Quantum efficiencies for chromium(VI) disappearance, Φ-cr(v1). approaches 37% at [Cr(VI)]0 = 200 μM. The interactions between Cr(VI)/AR and Cr(VI)/TiO2 are analyzed in detail. Spectroscopic evidence is presented for the first time that Cr(VI) forms a charge-transfer complex with TiO2 nanoparticles that could be excited by visible light (λ < 440 nm). The environmental implications of the above findings are briefly discussed. © 2008 American Chemical Society. |
| author |
Litter, Marta Irene |
| author_facet |
Litter, Marta Irene |
| author_sort |
Litter, Marta Irene |
| title |
Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| title_short |
Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| title_full |
Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| title_fullStr |
Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| title_full_unstemmed |
Photoinduced reactivity of strongly coupled TiO2 ligands under visible irradiation: An examination of an alizarin red@TiO2 nanoparticulate system |
| title_sort |
photoinduced reactivity of strongly coupled tio2 ligands under visible irradiation: an examination of an alizarin red@tio2 nanoparticulate system |
| publishDate |
2008 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_19327447_v112_n42_p16532_DiIorio http://hdl.handle.net/20.500.12110/paper_19327447_v112_n42_p16532_DiIorio |
| work_keys_str_mv |
AT littermartairene photoinducedreactivityofstronglycoupledtio2ligandsundervisibleirradiationanexaminationofanalizarinredtio2nanoparticulatesystem |
| _version_ |
1768545303577755648 |