Synthesis of Eu-doped TiO₂ nanoparticles by hydrothermal method

Abstract

   Purpose of research. Synthesis, characterization and comparison of the photocatalytic properties of europium-doped titanium dioxide nanoparticles.   Methods. Europium-doped titanium dioxide nanoparticles were synthesized via a hydrothermal method followed by post-treatment processes including washing and annealing. Characterization was conducted using transmission electron microscopy, X-ray phase analysis, and energy-dispersive analysis. The bandgap width of the nanoparticles was determined through diffuse reflectance spectroscopy. Photoluminescence properties were studied using scanning probe microscopy and Raman spectroscopy. The photocatalytic properties were studied by spectrophotometry to determine the degradation of methylene blue under ultraviolet radiation.   Results. Transmission electron microscopy identified the average particle sizes of europium-doped titanium dioxide. Using X-ray phase analysis, it was established that the nanoparticles were in the anatase phase regardless of the europium content percentage. Energy-dispersive spectroscopy confirmed the presence of the dopant in the samples. The photoluminescence intensity peak increased proportionally with the increase in europium content percentage. The strongest photocatalytic properties were exhibited at the lowest europium content among the samples studied.   Conclusion. Synthesized and processed europium-doped titanium dioxide nanoparticles with anatase polymorphic modification exhibit photoluminescent properties. The luminescence intensity depends on the concentration of europium in the particles, due to the formation of additional energy levels inside the band gap. The photocatalytic properties of europium-doped nanoparticles are significantly improved in comparison with samples synthesized without impurities. However, a europium concentration above 0,5% leads to the growth of structural defects that reduce the mobility of photogenerated charge carriers and creates a high energy barrier that prevents them from reaching the surface.