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Structural and photocatalytic characterisation of pyrogenic WOx-TiO2 nanoparticles.
|Katarzyna A. Michalow 1,2, Andri Vital 1, Kranthi K. Akurati 1, Katarzyna E. Zakrzewska 2, Giuseppino Fortunato 3, Felix Reifler 3, Axel Ritter 3, Thomas J. Graule 1, Mieczysław Rękas 2|
1. Empa, Swiss Federal Laboratories for Materials Testing and Research, High Performance Ceramics, Ueberlandstrasse 129, Dübendorf 8600, Switzerland
This work considers synthesis, characterization of structure and morphology of undoped, W-doped TiO2 and WOx/TiO2 composite nanoparticles with focus on photocatalytic application.
Nanoparticles with defined W/Ti ratio in the range of 0.1-10at% W were produced by a flame spray process using diluted metal-organic precursors and metal salt solutions. Specific surface area of the powders was controlled by the precursor flow rate at a constant volume flow of oxygen (atomizing and oxidizing gas). The combustion stoichiometry in the flame influenced the crystallinity of the particles, oxidation state and structural arrangement of the constituents.
The specific surface area of the as-synthesized powders was between 40 and 140 m2/g depending on the process parameters and tungsten concentration. Transmission electron microscopy (TEM) showed that the powders consist of nanoscaled spheres. Anatase is the prominent phase, and X-ray photoelectron spectroscopy (XPS) revealed that the valence of tungsten is related to the combustion stoichiometry in the flame. The band gap energy of the powders was determined by spectrophotometric measurements. The photocatalytic performance of the nanopowders under visible (400-500nm) and UV-A (365nm) light irradiation was studied for the degradation of methylene blue (MB) and methylene orange (MO) in aqueous suspension as well as decomposition of gas phase pollutants. The influence of W-concentration and specific surface area on the catalytic activity was determined.
We thank to the Polish Ministry of Science and High Education for the financial support, project no. R15 019 02.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium A, by Katarzyna A. Michalow
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-11 16:53 Revised: 2009-06-07 00:44