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Titolo:
Surface modification of TiO2 nanoparticles with carotenoids. EPR study
Autore:
Konovalova, TA; Kispert, LD; Konovalov, VV;
Indirizzi:
Univ Alabama, Dept Chem, Tuscaloosa, AL 35487 USA Univ Alabama TuscaloosaAL USA 35487 Dept Chem, Tuscaloosa, AL 35487 USA Russian Acad Sci, Inst Chem Kinet & Combust, SB, Novosibirsk 630090, Russia Russian Acad Sci Novosibirsk Russia 630090 B, Novosibirsk 630090, Russia
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 22, volume: 103, anno: 1999,
pagine: 4672 - 4677
SICI:
1520-6106(19990603)103:22<4672:SMOTNW>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTRON-PARAMAGNETIC-RESONANCE; COLLOIDAL TIO2; SEMICONDUCTOR PHOTOCATALYSIS; PARTICULATE SYSTEMS; TITANIUM-DIOXIDE; TRAPPED HOLES; REDUCTION; DYNAMICS; PHOTOELECTROCHEMISTRY; PHOTOLYSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
38
Recensione:
Indirizzi per estratti:
Indirizzo: Kispert, LD Univ Alabama, Dept Chem, Box 870336, Tuscaloosa, AL 35487 USA Univ Alabama Box 870336 Tuscaloosa AL USA 35487 , AL 35487 USA
Citazione:
T.A. Konovalova et al., "Surface modification of TiO2 nanoparticles with carotenoids. EPR study", J PHYS CH B, 103(22), 1999, pp. 4672-4677

Abstract

EPR measurements demonstrate efficient charge separation on carotenoid-modified titanium dioxide nanoparticles (7 nn). Strong complexation of carotenoids containing terminal carboxy groups (-CO2H) with the TiO2 surface leadsto electron transfer from the adsorbed carotenoid molecule to the surface trapping site. For these systems, EPR signals of the carotenoid radical cations Car(.+) and the electrons trapped on the TiO2 are observed before irradiation (77 K). Their UV-visible spectra show an absorption band with a maximum near 650 nm that is characteristic of the trapped electrons. Surface modification of the TiO2 by other carotenoids results in the formation of a complex with an optical absorption band near 545 nm. These systems form charge-separated pairs [Car(.+)... TiO2(e(tr)(-))(surf). TiO2(e(tr)(-))(latt.)] only upon 365-600 nm illumination at 77 K. Complexation of the TiO2 colloids with carotenoids enhances spatial charge separation, shifts the absorption threshold; into the visible region, and thus greatly improves the reducing ability of the semiconductor. Photoreduction of acceptor molecules suchas 2,5-dichloro-1,4-benzoquinone, nitrobenzene, and oxygen is demonstrated.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/09/20 alle ore 10:54:08