Enhanced Photoluminescence of Europium-Doped TiO₂ Nanoparticles Using a Single-Source Precursor Strategy

TiO₂:Eu³⁺ nanoparticles with varying europium concentrations were successfully synthesized via a one-pot sol-gel approach using a molecular heterometallic single-source precursor (SSP) Eu-Ti. For comparison, nanomaterials with similar europium levels were also produced by impregnating europium salts onto the same TiO₂ substrate. All the nanomaterials were thoroughly characterized using Eu elemental analysis, powder X-ray diffraction (XRD), scanning (SEM), transmission (TEM), scanning transmission electron microscopy (STEM), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and photoluminescence (PL). This low-temperature synthesis yielded crystalline powders, and calcination at 400 °C was performed to remove surface organic impurities, enabling a precise comparison of the final nanomaterials. While both preparation methods produced materials with similarly dispersed and localized dopants on the TiO₂ surface, photoluminescence studies revealed that the SSP-derived nanomaterials exhibited significantly superior electro-optical properties. This enhanced efficiency is attributed to the co-hydrolysis of both reactants, which facilitates an optimized interface between the crystalline TiO₂ core and the dopant-rich amorphous surface, thereby enabling far more effective charge transfer than that achieved by impregnation.