Improvement of charge separation in TiO{sub 2} by its modification with different tungsten compounds

Highlights: • Ammonium m-tungstate doped to TiO{sub 2} highly improved charge separation in TiO{sub 2}. • Negative electrokinetic potential of TiO{sub 2} facilitates holes migration to its surface. • Fast migration of holes to TiO{sub 2} surfaces increased yield of OH radicals formation. • Adsorptio...

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Bibliographic Details
Published inMaterials research bulletin Vol. 76
Main Authors Tryba, B., Tygielska, M., Grzeskowiak, M., Przepiorski, J.
Format Journal Article
LanguageEnglish
Published United States 15.04.2016
Subjects
ADSORPTION
DECOMPOSITION
DOPED MATERIALS
ELECTROCHEMISTRY
HOLES
HYDROGEN COMPOUNDS
HYDROXYL RADICALS
MATERIALS SCIENCE
METHYLENE BLUE
PHOTOCATALYSIS
PHOTOELECTRON SPECTROSCOPY
SURFACE PROPERTIES
SURFACES
SYNTHESIS
TITANIUM OXIDES
TUNGSTATES
TUNGSTEN OXIDES
VISIBLE RADIATION
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Summary:Highlights: • Ammonium m-tungstate doped to TiO{sub 2} highly improved charge separation in TiO{sub 2}. • Negative electrokinetic potential of TiO{sub 2} facilitates holes migration to its surface. • Fast migration of holes to TiO{sub 2} surfaces increased yield of OH radicals formation. • Adsorption of dyes on photocatalyst increased its decomposition under visible light. - Abstract: Three different tungsten precursors were used for TiO{sub 2} modification: H{sub 2}WO{sub 4}, WO{sub 2}, and ammonium m-tungstate. It was proved that modification of TiO{sub 2} with tungsten compounds enhanced its photocatalytic activity through the improvement of charge separation. This effect was obtained by coating of TiO{sub 2} particles with tungsten compound, which changed their surficial electrokinetical potential from positive onto negative. The most efficient tungsten compound, which caused enhanced separation of free carriers was ammonium m-tungstate (AMT). Two dyes with different ionic potential were used for the photocatalytic decomposition. It appeared that cationic dye—Methylene Blue was highly adsorbed on the negatively charged surface of TiO{sub 2} modified by AMT and decomposed, however this photocatalyst was quickly deactivated whereas anionic dye—acid red was better adsorbed on the less acidic surface of TiO{sub 2} and was rapidly decomposed with almost the same rate in the five following cycles.
ISSN:0025-5408
1873-4227
DOI:10.1016/J.MATERRESBULL.2015.12.001