Investigation of the Photocatalytic Efficiencies of Plasma Sprayed TiO_2-Fe_3O_4 Coatings

摘要

Owing to the much concern with global environmental problem, photocatalytic TiO_2 coatings were obtained using plasma spraying technique. The influences of the content of Fe_3O_4 additive to the TiO_2 powder on the phase composition, microstructure and photo-absorption of plasma sprayed TiO_2 coatings were systematically studied. The photocatalytic efficiency of the sprayed coatings is evaluated through the photo mineralization 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 TiO_2-Fe_3O_4 coatings consist of anatase TiO_2, rutile TiO_2 and FeTiO_3 ilmenite, and Fe_2TiO_5 pseudobrookite phase appears when the content of Fe_3O_4 additive is equal to or over 10%. The content of anatase TiO_2 in the sprayed coatings decreases from 14.8% to 5.9% with the increasing of Fe_3O_4 content to 32.6%. It was found that TiO_2 coatings can decompose acetaldehyde under the illumination of ultraviolet rays, and the degrading efficiency is improved with an increase in the content of FeTiO_3 in the coatings. However, the presence of large amount of Fe_2TiO_5 compound will substantially lower the photocatalytic efficiency of the sprayed TiO_2-Fe_3O_4 coatings for the unfavorable photo-excited electron-hole transfer process.