Optical and photocatalytic properties of Er3+ and/or Yb3+ doped TiO2 photocatalysts

TiO2 and rare earth ions (Er3+ and/or Yb3+) doped TiO2 photocatalysts were synthesized by a hydrothermal method. The obtained photocatalysts were characterized by XRD, TEM, EDX and Raman. XRD and Raman results indicate the formation of single anatase phase for all of samples. The TEM images suggest the obtaining of photocatalysts with irregular morphology. The influence of Er3+ and/or Yb3+ doping on luminescent and photocatalytic properties was investigated. TiO2 and rare earth ions doped TiO2 exhibit an emission band centered at about 520 nm under the excitation at 330 nm and the Er3+ and/or Yb3+ doping decreases the intensity of the emission. The lower emission intensity suggests the lower recombination rate of photogenerated electron–hole pairs, which leads to the higher photovoltaic efficiency of TiO2. Er3+ and/or Yb3+ doping inside the matrix can serve as an electron–hole trap by altering the electron–hole pair recombination.