Effect of co-doped La3+/halogen on visible light photocatalytic activity of TiO2

La3+/halogen (F-, Cl- and Br-) co-doped TiO2 was synthesized by alkoxide hydrolysis method. The prepared La3+/halogen TiO2 photocatalysts with anatase phases and rutile phases were characterized with XRD, EDS, TEM and surface area analytic technology. Methyl orange was used as model pollutants to evaluate its visible light photocatalytic activity. The results showed that the co-doping of La3+ and halogen ions improved the surface area of TiO2. Compared with 450 degrees C and 650 degrees C, La3+/Cl- and La3+/Br- co-doped TiO2 calcined at 550 degrees C exhibited much higher photocatalytic activity. The optimal doping ratio of La3+/F-, La3+/Cl- and La3+/Br- was 0.4, 0.6, and 0.5 ((wt%)/(wt%)), respectively. Moreover, the degradation ratio of methyl orange on La3+/halogen co-doped TiO2 with the optimal ratio were all higher than the maximum degradation ratio on La3+, F-, Cl- and Br- doped TiO2 prepared by the same method.