Autori: F.L. Toma, G. Bertrand, S. Begin, C. Meunier, O. Barres, D. Klein, C. Coddet

Editorial: Applied Catalysis B: Environmental, 68, p.74-84, 2006.

Rezumat:

This paper deals with the elaboration of titanium dioxide coatings, designed for photocatalytic applications, obtained by a non-conventional
method of deposition, suspension plasma spraying (SPS), an alternative of the atmospheric plasma spraying (APS) in which the material feedstock
is a suspension of the material powder to be sprayed. TiO2 P25 powder (Degussa AG) mechanically dispersed in distilled water and/or ethanol was
injected in argon–hydrogen and argon–hydrogen–helium plasma under atmospheric conditions. Scanning electron microscopy and X-ray
diffraction were performed to study the morphology and the crystalline phases of the titania coatings. Surface features were investigated by
Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Photocatalytic efficiency of the elaborated samples was tested in
an environmental test chamber set-up and evaluated from the conversion rate of nitrogen oxides.
The results showed that the coating obtained from the injection of an alcoholic suspension contained 23% of anatase ratio and ensured a very
low photocatalytic decomposition of nitrogen oxides. In contrast, the injection of an aqueous suspension into the plasma permitted to obtain
deposits where the anatase phase and the crystallites size were preserved. Also, a conversion rate of the pollutants of about 40%, slightly better
compared to that of the initial P25 powder (around 32%) was noticed. This slightly higher efficiency was correlated with a cleaning of the particles
surfaces when crossing the plasma and a higher hydroxylation of the coating surface.

Cuvinte cheie: Photocatalysis; TiO2; Suspension plasma spraying; Nitrogen oxides; FT-IR; XPS

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