Microstructural, chemical and photocatalytic properties of strontium gadolinium oxide doped with Tm3+ and Yb3+ ions

Abstract

This is the first report of photocatalytic degradation employing SrGd₂O₄ nanoparticles doped with Tm³⁺ and Yb³⁺ ions. The sample was prepared via the sol-gel assisted combustion method using concentrations of 1 at% Tm³⁺ and 4 at% Yb³⁺. An X-ray Diffraction (XRD) investigation showed that all diffraction peaks are allocated to a pure orthorhombic phase. Transmission and Scanning Electron Microscopy (TEM, SEM) revealed the existence of porous agglomerated round-shaped particles, arranged in network-like structures. Energy Dispersive X-ray Spectroscopy (EDS) verified the presence of all structural elements, as well as their uniform distribution across the particles. UV-VIS Diffuse Reflectance Spectroscopy (UV-VIS DRS) enabled determination of the band gap, which was calculated to be 4.3 eV. X-ray Photoelectron Spectroscopy (XPS) revealed the presence of OH⁻ groups on the material surface. Photocatalytic properties were observed through the degradation of Methylene Blue. The results indicated that after 4 h of exposure to the simulating sun irradiation, about 50 % of the initial dye concentration was mineralized.