XAS studies of Sn modified $\mathrm{TiO_{2}}$ coatings
| Autor: | Maver, Ksenija, Arcon, Iztok, Lavrencic Stangar, Urska |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Zdroj: | European Conference on X-Ray Spectrometry, EXRS-2018, Ljubljana, Slovenia, 2018-06-24-2018-06-29 |
| DOI: | 10.3204/pubdb-2018-03473 |
| Popis: | European Conference on X-Ray Spectrometry, EXRS-2018, Ljubljana, Slovenia, 24 Jun 2018 - 29 Jun 2018 Coatings based on $\mathrm{TiO_{2}}$ are extensively investigated material for the preparation of surfaces which are referred as self-cleaning. Under solar illumination these coatings catalyze pollutants degradation and enhance their removal from the surface due to photoinduced superhydrophilicity [1]. There are two main drawbacks of using pure $\mathrm{TiO_{2}}$ (anatase) as a photocatalyst; i) its band gap lies in the UVA region so it can exploit only a part of the sunlight spectrum, and ii) it has a high degree of recombination between photo generated electrons and holes on the surface. There are various strategies to improve the photocatalytic efficiency of $\mathrm{TiO_{2}}$, one of them is the modification with transition metals. Based on our previous experiences with sol-gel synthesis of low-temperature $\mathrm{TiO_{2}}$ thin films [2], we prepared a series of Sn modified $\mathrm{TiO_{2}}$ photocatalysts. As a starting material only organic (Ti and Sn alkoxide) precursors were used. The loadings of Sn cations were varied in the range of 0.05 to 20 mol.%. The coatings, deposited on glass substrates by dip-coating technique, were dried at 150 oC. In addition, another set of photocatalyst coatings was prepared by further calcination at 500 °C in air. The comparison of photocatalytic activities of Sn modified $\mathrm{TiO_{2}}$ to unmodified $\mathrm{TiO_{2}}$ showed that Sn loadings in the range of 1-10 mol.% improved photocatalytic activity up to 8 times. At lower loadings of Sn, the photocatalytic activity was improved only by 30 %. After the coatings are calcined, their photocatalytic activity was significantly reduced.The objective of the research was to examine the mechanism responsible for photocatalytic properties of Sn modified $\mathrm{TiO_{2}}$ and to to clarify the role of Sn cations in the $\mathrm{TiO_{2}}$ photocatalytic process. For this purpose, Sn and Ti K-edge XANES and EXAFS analysis was used to precisely determine the local structure and the site of incorporation of Sn cations on titania nanoparticles in the coatings. We examined the hypothesis that the solid-solid interface was a crucial structural feature that facilitates charge separation and enhances photocatalytic efficiency of titania. |
| Databáze: | OpenAIRE |
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