The photocatalytic activity and photo-absorption of plasma sprayed TiO2-Fe3O4 binary oxide coatings

To inhibit the rapid recombination of exited electrons and holes and improve the illumination absorption of the TiO2 based photocatalyst during photocatalysis, one kind of novel TiO2-Fe3O4 coating was prepared by plasma spraying. The effects of spraying parameters and the Fe3O4 additive to anatase TiO2 powder on the microstructure, surface morphology and photo-absorption of plasma sprayed TiO2 coatings were systematically studied. The photocatalytic activity of the sprayed coatings is evaluated through the photo-degradation of acetaldehyde. The UV-VIS-NIR absorption spectra of the deposited coatings were obtained by using Shimadzu UV-3100PC scanning spectrophotometer. The results showed that the TiO2-Fe3O4 coatings consist of anatase TiO2, rutile TiO2, Fe3O4 and FeTiO3, and the content of anatase TiO2 was estimated to be approximately 4%, which is lower than that of TiO2 coatings of from 8% to 15%. With an increase in plasma arc power, the content of anatase TiO2 in the coatings decreased. It was found that TiO2 coatings deposited on mild steel can decompose acetaldehyde under the illumination of ultraviolet rays, and the degrading activity is improved with an increase in the content of anatase TiO2 in the coatings. Moreover, the addition of Fe3O4 can enhance the photocatalytic activity for the formation of FeTiO3 Compound in the TiO2-Fe3O4 coatings. (C) 2002 Elsevier Science B.V. All rights reserved.