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

Abstract

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.

Nanostructure and Optical Property Investigations of SrTiO3 Films Deposited by Magnetron Sputtering

“…Figure 6a shows that the refractive index increases with annealing temperature before annealing at 700 °C, and decreases with annealing temperature after annealing at 700 °C. Such a change is attributed to different values of packing density p of the films [9,10], which can be calculated from Lorentz-Lorenz relation [20], p=(n2−1n2+2)true/(nb2−1nb2+2) where n b is the refractive index of bulk SrTiO 3 . Taking n b = 2.432 at 550 nm, the values of packing densities are 0.86, 0.87, 0.96, 0.94 and 0.93 for the as-deposited film and films annealed at 500 °C, 600 °C, 700 °C and 800 °C, respectively.…”

“…Meanwhile, the absorption edge moves toward lower photon energy at higher annealing temperatures. The absorption peak of the SrTiO 3 thin film in high photon energy regions comes from the electronic inter-band transition [9]. Hence, the movements of absorption edges are related to the varieties of the bandgap structures in SrTiO 3 thin films.…”

“…SrTiO 3 thin films can be fabricated by many depositional techniques. Chemical techniques include atomic layer deposition (ALD) [7], metal organic vapor deposition (MOCVD) [8], and the sol-gel process [9], among others. Physical techniques include pulsed laser deposition (PLD) [10] and magnetron sputtering [11,12,13], among others.…”

Dy(III) Doped BiOCl Powder with Superior Highly Visible-Light-Driven Photocatalytic Activity for Rhodamine B Photodegradation

“…Foreign ion doping has been widely adopted to increase the visible light absorption for single phase photocatalysts, because this process can generate a doping level between the conduction band (CB) and valence band (VB) [ 8 ]. Consequently, the energy required to excite electrons is decreased, and the light response of semiconductors is enhanced.…”

Investigation of Structural and Optical Properties of Amorphous-Crystalline Phase Transition of As40S45Se15 Thin Films

“…The values of the Cauchy coefficients a and b are tabulated in Table V. Such a change is attributed to different values of packing density p of the thin films [42,43], which can be computed from the Lorentz-Lorenz relation [44]: On the other hand, for the annealing temperature at 380 K, the packing density increases to a maximum value. After annealing at around 390, 400, and 410 K, the packing density presents a tendency of decreasing until it reaches a smaller value at 410 K, which is attributed to the presence of cracks in the films at higher annealing temperatures.…”