Enhancement of the photoinduced electron transfer from cationic dyes to colloidal TiO2 particles by addition of an anionic surfactant in acidic media

摘要

The absorption and emission characteristics of a cationic dye rhodamine B (RB) were observed in highly acidic colloidal TiO2 aqueous solution and the same spectra of synthesized n-hexadecylrhodamine B (C-16-RB) were also analyzed to get further realization of RE. Since both the TiO2 surface and the dyes used are positively charged in acidic media, there is almost no adsorption of dye molecules on the surface of TiO2 particles. By addition of an anionic sodium dodecylbenzensulfonate (DBS) surfactant, the mutual interaction among dyes, DBS and TiO2 is very strong according to the absorption and emission spectral analysis. Anionic DBS molecules can modify the positively charged TiO2 surface and make the same positively charged dyes assess to the TiO2 surface. The distance between the dye and TiO2 surface can affect the photoinduced electron transfer efficiency from dye molecules to the TiO2 particles. This is well demonstrated by comparing RB with C-16-RB by the fluorescence quenching efficiency in the TiO2/DBS and the TiO2-free systems. The photodegradation of RE in the TiO2/DBS system by visible light irradiation under either air-saturated or oxygen-free conditions also verify the conclusion that the dye RE can inject electrons to semiconductor particles much more efficiently after modification of the TiO2 surface by an anionic surfactant. (C) 1998 Elsevier Science B.V. [References: 27]