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


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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Available from: Zhichun Si, Oct 01, 2015
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    • "The Sm 3+ ion with 4f electron configurations into semiconductor lattice can act as an electron reservoir to trap electrons and increases the separation rate of electron–hole pairs [14] [15] [16]. In addition, Sm 3+ ion doping can establish a means to concentrate the contaminant molecules at the semiconductor surface and enhances the light sensitivity of semiconductor particles [17]. On the other hand, oxygen molecules on the semiconductor surface act as an electron 1350-4177/Ó 2015 Elsevier B.V. All rights reserved. "
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    ABSTRACT: Pure and samarium doped ZnO nanoparticles were synthesized by a sonochemical method and characterized by TEM, SEM, EDX, XRD, Pl, and DRS techniques. The average crystallite size of pure and Sm-doped ZnO nanoparticles was about 20nm. The sonocatalytic activity of pure and Sm-doped ZnO nanoparticles was considered toward degradation of phenazopyridine as a model organic contaminant. The Sm-doped ZnO nanoparticles with Sm concentration of 0.4mol% indicated a higher sonocatalytic activity (59%) than the pure ZnO (51%) and other Sm-doped ZnO nanoparticles. It was believed that Sm(3+) ion with optimal concentration (0.4mol%) can act as superficial trapping for electrons in the conduction band of ZnO and delayed the recombination of charge carriers. The influence of the nature and concentration of various oxidants, including periodate, hydrogen peroxide, peroxymonosulfate, and peroxydisulfate on the sonocatalytic activity of Sm-doped ZnO nanoparticles was studied. The influence of the oxidants concentration (0.2-1.4gL(-1)) on the degradation rate was established by the 3D response surface and the 2D contour plots. The results demonstrated that the utilizing of oxidants in combination with Sm-doped ZnO resulting in rapid removal of contaminant, which can be referable to a dual role of oxidants; (i) scavenging the generated electrons in the conduction band of ZnO and (ii) creating highly reactive radical species under ultrasonic irradiation. It was found that the Sm-doped ZnO and periodate combination is the most efficient catalytic system under ultrasonic irradiation.
    Ultrasonics Sonochemistry 09/2015; 28:169-77. DOI:10.1016/j.ultsonch.2015.07.012 · 4.32 Impact Factor
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    • "The lanthanide ions with 4f electron configurations into TiO 2 lattice can act as an electron reservoir to trap electrons and significantly increase the separation rate of generated electron–hole pairs, resulting in the improvement of the catalytic activity [27] [28] [29]. On the other hand, lanthanide ions doping can enhance the light sensitivity of catalyst and provide a means to concentrate the organic pollutant at the catalyst surface [30] [31]. "
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    ABSTRACT: In this work, pure TiO2 and samarium, cerium mono-doped and co-doped TiO2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their sonocatalytic efficiency studied toward removal of Methyl Orange as a model organic pollutant from the textile industry. The relationship of structure and sonocatalytic performance of catalysts was established by using various techniques, such as XRD, TEM, SEM, EDX, DRS, and PL. A comparison on the removal efficiency of sonolysis alone and sonocatalytic processes was performed. The results showed that the samarium, cerium co-doped TiO2 catalyst with narrower band gap energy and smaller particle size leads to a rapid removal of pollutant. It was believed that Sm(3+) and Ce(4+) ions can serve as superficial trapping for electrons at conduction band of TiO2 and prolonged the lifetime of electron-hole pairs. Finally, the effect of synthesis and operational variables on the sonocatalytic activity of co-doped TiO2 catalyst was studied and optimized using response surface methodology as a statistical technique. The results showed that the maximum removal efficiency (96.33%) was achieved at the optimum conditions: samarium content of 0.6wt%, cerium content of 0.82wt%, initial pollutant concentration of 4.31mgL(-1), catalyst dosage of 0.84mgL(-1), ultrasonic irradiation power of 700W, and irradiation time of 50min. Copyright © 2015 Elsevier B.V. All rights reserved.
    Ultrasonics Sonochemistry 02/2015; 26:281–292. DOI:10.1016/j.ultsonch.2015.02.001 · 4.32 Impact Factor
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    • "samples, a TA fluorescence probe was used to measure the level of hydroxyl radicals (ÅOH) generated in the reaction system. TA can quickly react with ÅOH to generate 2-hydroxyterephthalic acid, whose fluorescence intensity is proportional to the amount of ÅOH [67] [68]. Fig. 11d shows the comparison of fluorescence intensity for the prepared Fig. 10 – Photoelectrochemical properties of the prepared samples under illumination of stimulated solar light (AM 1.5, 100 mW/cm 2 ): (a) amperometric I–t curves at an applied potential of 1.23 V (vs. "
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    ABSTRACT: Coaxial heterogeneous graphene quantum dot-sensitized TiO2 nanotube arrays (GQDs/TNTs) are prepared by a coupling technique of linker molecule binding and electrophoretic deposition (EPD). The silane linker molecules act as a superb medium for integrating GQDs and TNTs by covalent amide linkage, thus preventing GQDs from clogging the tube entrances and forming a uniform GQD layer tightly attached to the inside tube walls during the following EPD process. By adjusting the time of EPD, appropriate thickness of the deposited GQDs in the internal tube walls of TNTs can be controlled. Compared to the pristine TNTs and GQDs/TNTs prepared by the conventional impregnation-precipitation method, the hybrids fabricated by EPD exhibit significantly enhanced photoelectrochemical water-splitting activity and photocatalytic organic dye decomposition performance for their broad photo-absorption range, fast separation of photogenerated charge, and stability.
    Carbon 01/2015; 81(1):474-487. DOI:10.1016/j.carbon.2014.09.080 · 6.20 Impact Factor
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