New Insights into Sensitization Mechanism of the Doped Ce (IV) into Strontium Titanate

SrTiO(3) and Ce(4+) doped SrTiO(3) 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 Ce(4+) doped SrTiO(3) systems. Sr(2+) in SrTiO(3) system was replaced by Ce(4+), which reduced the surface segregation of Ti(4+), ameliorated agglomeration, increased specific surface area more than four times compared with pure SrTiO(3), and enhanced quantum efficiency for SrTiO(3). Results showed that Ce(4+) doping increased the physical adsorption of H(2)O and adsorbed oxygen on the surface of SrTiO(3), which produced additional catalytic active centers. Electrons on the 4f energy level for Ce(4+) produced new energy states in the band gap of SrTiO(3), which not only realized the use of visible light but also led to an easier separation between the photogenerated electrons and holes. Ce(4+) repeatedly captured photoelectrons to produce Ce(3+), which inhibited the recombination between photogenerated electrons and holes as well as prolonged their lifetime; it also enhanced quantum efficiency for SrTiO(3). The methylene blue (MB) degradation efficiency reached 98.7% using 3 mol % Ce(4+) doped SrTiO(3) as a photocatalyst, indicating highly photocatalytic activity.