Influences of the factors on photocatalysis of fluorine-doped SrTiO ₃ made by mechanochemical method

Mechanochemical reaction method was used for preparing fluorine-doped SrTiO₃ and the influences of several parameters on the visible light photocatalysis of the samples were studied. In the samples of 5 mol% SrF ₂-SrTiO₃ ground for 10-240 min, the sample ground for 60 min showed the highest capability for the elimination of NO. The postgrinding heat treatment at appropriate temperature (150-200 °C) in air could improve the photo-oxidation capability of fluorine-doped SrTiO₃ probably due to the decrease in the number of hydroxyl groups on the surface of the powder in the sample. The samples made by 1-5 mol% SrF₂-SrTiO₃ mixtures showed high photocatalytic activity, whereas excess content of SrF ₂ resulted in decreasing activity due to the formation of a new fluoride compound in the sample. The sample prepared by grinding the mixture of 5 mol% SrF₂ and 95 mol% SrTiO₃ for 1 h followed by heat treatment at 150 °C for 2 h showed about three and two times larger photocatalytic activity for the elimination of NO under the irradiation of visible light (wavelength >510 nm) than pure SrTiO₃ and P-25, respectively.