Photodegradation activity of yttrium-doped SnO₂ nanoparticles against methylene blue dye and antibacterial effects

This review reports the effects of yttrium (Y) on the physicochemical characteristics of tin(II) dioxide (SnO₂) nanoparticles (NPs), which were efficiently synthesized via a simple hydrothermal chemical route with different doping concentrations (0, 2 and 4 at%) of Y. The structural, optical and photocatalytic properties of the as-prepared Y-doped SnO₂ (Y:SnO₂) NPs were investigated, and the results are described. X-ray diffraction (XRD) studies showed that the undoped and Y:SnO₂ NPs had a fine crystalline texture with a tetragonal structure and particle size range of 27–15 nm, although the size decreased with Y doping. High-resolution scanning electron microscopy (HRSEM) morphological analysis revealed spherical NPs forming agglomerates. Optical absorption was investigated by UV-visible diffuse reflectance spectroscopy, and showed a redshift in bandgap energy for Y³⁺-doped SnO₂ NPs, and photoluminescence spectroscopy revealed the most intense emission peaks in the visible light region. Enhanced photocatalytic activity was observed for the doped samples, and the 4% Y:SnO₂ NPs exhibited excellent photodegradation of methylene blue aqueous (MB) dye in visible light, demonstrating 92.34% degradation in 180 min. The other photocatalysts also demonstrated greater than 85% photodegradation efficiency and high stability, with no significant reduction in activity observed after five cycles. The results indicate that the superoxide (^·O₂⁻) radical, a key reactive species, played a vital role in the degradation of aqueous MB dye. The probable photocatalytic mechanism of the Y:SnO₂ NPs was thoroughly investigated.