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New type of photoactive materials based on TiO2 modified by anthraquinone derivatives

Mech K., Szaciłowski K.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 1

269-273

EN

Anthraquinone derivatives chemisorbed at nanocrystalline TiO2 present a new type of photoactive hybrid materials. These systems consist of organic chromophores anchored to the semiconductor surface via oxygen atoms of hydroxyl or carbonyl group. The bond between the chromophore and the titanium atom at the semiconductor surface reveals strong covalent character which makes the material stable in wide spectrum of electric potential and in an acidic environment. In alkaline solutions hydrolysis can be observed. The electrodes made of a modified TiO2 generate photocurrents within 300-700 nm, compared, with 300-400 nm for unmodified TiO2. Such an efficient photosensitization is a result of mutual arrangement of energy levels of the molecule and energy bands of the semiconductor.

PL

Zaadsorbowane na powierzchni nanokrystalicznego dwutlenku tytanu pochodne antrachinonu tworzą nowy rodzaj fotoaktywnych materiałów hybrydowych. Układy te są zbudowane z organicznych barwników zakotwiczonych na powierzchni półprzewodnika poprzez atomy tlenu grup hydroksylowych lub karbonylowych. Wiązanie pomiędzy barwnikiem a atomem tytanu na powierzchni półprzewodnika wykazuje silny charakter kowalencyjny, co czyni materiał stabilnym w szerokim zakresie potencjałów, a także w srodowisku kwasnym. W srodowisku zasadowym materiał ulega hydrolizie. Elektrody na bazie modyfikowanego TiO2 generuja fotoprady w zakresie 300-700 nm, podczas gdy elektrody z czystego TiO2 daja fotoprady w zakresie 300-400 nm. Tak wydajną fotosensybilizacją jest wynikiem wzajemnego położenie poziomów energetycznych cząsteczki oraz pasmami półprzewodnika.

2

Photosensitized decomposition of textile dyes on TiO2-Tytanpol A11 and TiO2-Degussa P25

Zielińska B., Morawski A. W., Kaleńczuk R. J.

Polish Journal of Chemical Technology

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2006

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Vol. 8, nr 3

150-152

EN

The photoassisted decomposition of five organic dyes (Reactive Red 198 (RR198), Reactive Black 5 (RB5), Acid Black 1 (AB1), Direct Green 99 (DG99) and Acid Blue 7 (AB7)) has been investigated in aqueous solution in the presence of two kinds of TiO2 photocatalysts: TiO2-Tytanpol A11 (,,Police" Chemical Factory, Poland) and TiO2-Degussa P25 (,,Degussa" Germany) and under the illumination by the Vis light. The results suggest that the value of the adsorption of the dyes on the photocatalyst surface is the controlling step of the photosensitized degradation of dyes. The A11 photocatalyst demonstrates higher activity than P25. This effect is diffrent from the one obtained under the UV illumination, where P25 shows a much higher activity. Additionally, it was investigated that for both phototocatalysts used the degree of dyes decomposition decreased with the increasing of the maximum absorption of the dyes.

3

Optical properties of ferroelectric Langmuir-Blodgett films impregnated with dye molecules

Zaitsev V. B., Nevzorov A. V., Plotnikov G. S.

Materials Science

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2002

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Vol. 20, No. 3

57-63

EN

Ferroelectric polymer films are very promising materials for modern microelectronics, molecular electronics and nonlinear optics. Langmuir-Blodgett films of poly vinylidene fluoride copolymer impregnated with organic dye molecules were studied experimentally. Ferroelectric films of this type undergo a phase transition at the Curie temperature. Fluorescence spectra of the structures were investigated. A strong influence of the phase transition onto the position and shape of the fluorescence spectrum was observed. A new effect of photosensitized shift of the Curie temperature was found. Besides the main ferroelectric transition, a low-temperature structural transition in super thin films was discovered for the first time by the optical method. Possible mechanisms of the effects observed are discussed.