Photoluminescence and Photocatalysis Properties of Dual-Functional Eu3+-Doped Anatase Nanocrystals

Red-color-emitting TiO 2:Eu 3+ nanophosphors have been synthesized through the hydrothermal process. Samples with different morphologies have been obtained by changing pH values of solution. The structural and luminescence properties of samples were investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis spectra, and photoluminescence (PL) spectra. Most importantly, surface photovoltage spectra were used to discuss the charge transfer process and further explained the luminescence phenomenon of different morphologies for the first time. The critical transfer distance for the Eu 3+ ions in TiO 2 matrix was calculated, and we could conclude that the concentration quenching process was attributed to the multipole–multipole interaction. The relative intensity ratios of 5 D 0 – 7 F 2 transition to 5 D 0 – 7 F 1 transition of TiO 2: x %Eu 3+ ( x = 2, 4, 6, 8, 10, 12) have been calculated to understand the lattice symmetry and coordination environment of Eu 3+ ions. The spectral characteristics and site symmetry have been discussed through the Judd–Ofelt parameters. Moreover, the investigation of photocatalytic ability of TiO 2: x %Eu 3+ showed that the photodegradation efficiencies decrease with an increase in the amount of Eu 3+ for the degradation of methyl orange under white light irradiation, and the photodegradation efficiency of TiO 2:2%Eu 3+ was 99% after 25 min, which is much more higher than that for TiO 2:12%Eu 3+ (25%).