Photocatalytic activity enhancement of TiO 2 porous thin film due to homogeneous surface modification of RuO 2
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bo Zhangb) and Yuan Lin Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China (Received 8 December 2010; accepted 7 April 2011)
Ruthenium dioxide (RuO2) was uniformly modified on TiO2 porous thin film by impregnation of Ru-contained dye on the film followed by sintering it at 450 °C to burn off organic matters and form ruthenium oxide, which is named as impregnation method. The homogenous modification of metal oxide inside porous thin film can be realized by the impregnation method, and the modification amount of RuO2 can be easily adjusted by the iteration numbers of impregnation and sintering. Appropriate amount of uniformly modified RuO2 was found to obviously enhance photocatalytic performance of TiO2 to degrade eosin Y. The photocatalysis enhancement was attributed to the shallow hole traps on the surface of nanoparticles formed by RuO2, and these traps can retard recombination of hole with electron. I. INTRODUCTION
With the rapid development of society and industrialization processes, the kinds and amount of organic pollutants in industrial effluents increase sharply, which causes a great challenge to the traditional water treatment process. Therefore, photocatalytic oxidation technology, as a very effective, nontoxic, energy-saving, nonsecondary pollution procedure for the degradation of a variety of organic contaminants, has drawn a considerable attention.1,2 Nanocrystalline semiconductor TiO2, which is an abundant, nontoxic, chemically stable, effectual photocatalyst, has been found to have extensive applications to solve these environmental problems, such as decomposition of inorganic and organic pollutants and toxic material in both liquid and gas phase systems.3,4 However, only the ultraviolet light (k , 387 nm), which occupies 4% of solar light energy, can be absorbed by pure anatase TiO2 to generate electron-hole pairs.5 For this reason, the practical photocatalytic application of TiO2 is limited. On the other hand, the photogenerated electron-hole pairs, which play the most important role during the photodegradation process, are liable to recombine, thus leading to the low efficiency of photocatalyst.6,7 Therefore, to enhance photocatalytic activity, it is paramount to extend the photoresponse of TiO2 to the visible region and to reduce the recombination of electron-hole pairs. Recently, to overcome the deficiencies of TiO2 mentioned earlier and then to improve its photocatalysis Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2011.124 1532
J. Mater. Res., Vol. 26, No. 12, Jun 28, 2011
http://journals.cambridge.org
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performance, many works have been attempted. These works include doping TiO2 with noble metals such as Pt, Ag, Au8–10 and with nonmetals such as N, S, C etc.,11–13 and sensitizing TiO2 with dye molecules and other compounds.14,15 According to the literature, the modifi
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