SrTiO₃ and Ce4+ doped SrTiO₃ were synthesized by a modified sol⁻gel process. The optimization synthesis parameters were obtained by a series of single factor experiments. Interesting phenomena are observable in Ce4+ doped SrTiO₃ systems. Sr2+ in SrTiO₃ system was replaced by Ce4+, which reduced the surface segregation of Ti4+, ameliorated agglomeration, increased specific surface area more than four times compared with pure SrTiO₃, and enhanced quantum efficiency for SrTiO₃. Results showed that Ce4+ doping increased the physical adsorption of H₂O and adsorbed oxygen on the surface of SrTiO₃, which produced additional catalytic active centers. Electrons on the 4f energy level for Ce4+ produced new energy states in the band gap of SrTiO₃, which not only realized the use of visible light but also led to an easier separation between the photogenerated electrons and holes. Ce4+ repeatedly captured photoelectrons to produce Ce3+, which inhibited the recombination between photogenerated electrons and holes as well as prolonged their lifetime; it also enhanced quantum efficiency for SrTiO₃. The methylene blue (MB) degradation efficiency reached 98.7% using 3 mol % Ce4+ doped SrTiO₃ as a photocatalyst, indicating highly photocatalytic activity.
Keywords: Ce(IV); doping modification; photocatalyst; strontium titanate.