TiO2/WO3 photocatalytic composite coatings prepared by spray pyrolysis

TiO2/WO3 composites supported on a stainless steel foil were prepared by the spray pyrolysis technique. Content of WO3 was gradually increased from 1 wt.% to 100 wt.%, while the coating thickness was limited to about 1 μm. The coatings were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The photocatalytic activity of obtained coatings was investigated by degradation of methyl orange, used as model pollutant. The results show that with increasing WO3 content up to 10 wt.% photoactivity increases as result of better charge separation that could effectively prevent the recombination of photogenerated electrons and holes. Further increase of WO3 content led to decrease of photoactivity.