Photocatalytic and photoluminescence properties of core-shell SiO2@TiO2:Eu3+,Sm3+ and its etching products

A novel multifunctional core–shell, yolk–shell SiO2@TiO2:Eu3+/Sm3+ and hollow TiO2:Eu3+/Sm3+ structures were successfully synthesized. The relationship between morphology/ions doping and multifunctional properties including photoluminescence and photocatalysis has been discussed in detail for the first time using systematic characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL), ultraviolet–visible light (UV-vis) analysis, Fourier transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). Upon ultraviolet (UV) excitation, the products show the characteristic red and orange–red emission lines of Eu3+ and Sm3+, respectively. In addition, Judd–Ofelt intensity parameters (Ω2, Ω4) were used to investigate the symmetry and coordination state of Eu3+ ions in the products with different morphologies. The relative luminescence inte...