Article

Photoinduced Hydroxyl Radical and Photocatalytic Activity of Samarium-doped TiO2 Nanocrystalline

School of Resources Processing and Bioengineering, Central South University, Changsha 410083, China.
Journal of Hazardous Materials (Impact Factor: 4.53). 02/2008; 150(1):62-7. DOI: 10.1016/j.jhazmat.2007.04.045
Source: PubMed

ABSTRACT

Sm(3+)-doped TiO(2) nanocrystalline has been prepared by sol-gel auto-combustion technique and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and also UV-vis diffuse reflectance spectroscopy (DRS). These Sm(3+)-doped TiO(2) samples were tested for methylene blue (MB) decomposition and *OH radical formation. The analysis of *OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with using terephthalic acid, which readily reacted with *OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. It was observed that the presence of Sm(3+) ion as a dopant significantly enhanced the photocatalytic activity for MB degradation under UV light irradiation because both the larger specific surface area and the greater the formation rate of *OH radical were simultaneously obtained for Sm(3+)-doped TiO(2) nanocrystalline. The adsorption experimental demonstrated that Sm(3+)-TiO(2) had a higher MB adsorption capacity than undoped TiO(2) and the adsorption capacity of MB increased with the increase of samarium ion content. The results also indicated that the greater the formation rate of *OH radical was, the higher photocatalytic activity was achieved. In this study, the optimum amount of Sm(3+) doping was 0.5 mol%, at which the recombination of photo-induced electrons and holes could be effectively inhibited, the highest formation rate of *OH radicals was, and thereby the highest photocatalytic activity was achieved.

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    • "Terephthalic acid readily serves as a probe molecule that reacts with Å OH to produce a highly fluorescent product (2-hydroxyterephthalic acid). The PL intensity of 2- hydroxyterephtalic acid is proportional to the quantity of Å OH radicals produced in solution171819. The experimental process is similar to the photocatalytic experiment; the mixed solution, which contains 5 Â 10 À4 M terephthalic acid and 2 Â 10 À3 M NaOH aqueous solution, replaced the rhodamine B solution during the photocatalytic experiment. After visible-light irradiation every 20 min, the reaction solution was applied to determine the increase of the PL intensity at 425 nm excited by 315 nm light[20]. "
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