Study On Preparation And Photocatalytic Property Of Dopping TiO₂

In this paper, sol-gel method was used to prepare TiO₂ nano-powder when n-butyl titanate was used as titanium source and anhydrous ethanol as solvent; and then the introduction of Fe dopping elements was from ferric nitrate to prepare (Ti_1-xFe_x)O₂ nano-powder with single anatase structure; and then lanthanum nitrate was used as the re-introduction of La dopping element to prepare (Ti_1-x-yFe_xLa_y)O₂ nano-powder with single anatase structure. TG-DTA, XRD, SEM, spectrophotometer and other modern analytical methods were used to test the thermal behavior of the gel; the structure, morphology and photocatalytic properties of the powder; The influence of preparation process on the structure, morphology and photocatalytic properties of TiO₂ nano-powder were studied. The test result found:In this experimental conditions, the undopped products synthesized within the limit of 350℃ 550℃are single anatase TiO₂; When the synthetic temperature reaches 650℃, there are 23.6 percent of the anatase phase transformed into rutile phase. With the synthetic temperature gradually increasing, the average grain size and the particle size of the TiO₂ nano-powder gradually increased. As the synthetic temperature reaches 650℃, the small-size particles have basically disappeared and the reunion levels gradually decreased, TiO₂ nano-powder of mixed crystal type has the best photocatalytic property, at the moment, the degradation rate of methyl orange is 51 percent.(Ti_1-xFe_x)O₂(x= 0.01%, 0.03%, 0.05%) nano-powder synthesized at 650℃are all in the form of single anatase phase, iron-dopping inhibited the transformation of anatase phase into rutile phase. With the molar dosage concentration of Fe3+ ion x gradually increasing, the average grain size of the (Ti_1-xFe_x)O₂ nano-powder firstly increased and then decreased, there is significantly refinement comparing with non-dopped TiO₂ nano-powder; and the particle size also significantly reduced at the monment small size of particles are in the dominance and the reunion phenomenon improved with morphology diversity of the particle. When the iron ion dosage concentration x is 0.03 percent, the average grain size of the powder are 5.497nm coming up to the smallest and the degradation rate of methyl orange is 87.5 percent at the best photocatalytic property 36.5 percent better than the non-dopped TiO2 nano-powder.When the ion dosage concentration sum of the Fe³⁺ and La³⁺ is 0.03 percent, (Ti_1-x-yFe_xLa_y)O₂(x+y=0.03%; y/x=1/5, 1/2, 5/1, 6/0) nano-powders synthesized at 650℃are also the TiO2 of single anatase structure, co-dopping with Fe³⁺ and La³⁺ ion could also inhibited the transformation of anatase phase into rutile phase. With the La³⁺ and Fe³⁺ ion co-dopping concentration molar ratio y/x gradually increasing, the average grain size and the particle size both have more obviously refinement in different degree as the uniform particle size is in distribution and the agglomeration even more seriously. After the La³⁺ ion co-dopped with Fe³⁺ ion, the photocatalytic property of (Ti_1-x-yFe_xLa_y)O₂ nano-powder significantly increased. With the co-dopping concentration molar ratio y/x comes up to 1/2, the photocatalytic property of (Ti_1-x-yFe_xLa_y)O₂ nano-powder 41 percent better than undopped nano-powder.