Enhanced Photocatalytic Degradation and Synergistic Effects of Metal-Ion-Doped Tin Oxide Nanoparticles for Water Remediation

Graphical Al, Ga, and In are doped into SnO2 through the hydrothermal method, leading to changes in its bandgap and consequently improving the photocatalytic capability of SnO2. Tin oxide, particularly tin dioxide (SnO₂), exhibits excellent potential as a photocatalyst in wastewater treatment. Tin oxide nanocomposites were synthesized via a liquid-phase method using tin tetrachloride pentahydrate as the precursor and Al 3 ⁺, Ga 3 ⁺, and In 3 ⁺ ions as dopants. The samples were characterized by XRD, SEM, UV–vis spectroscopy, and so on. SEM images revealed that the doped nanoparticles formed denser aggregates with irregular coarse-cubic morphologies. XRD patterns of Al-, Ga-, and In-doped SnO₂ showed no impurity peaks, confirming their high crystallinity and phase purity. Doping modifies the energy band structure and introduces impurity levels, thereby enhancing visible-light absorption and inducing a redshift. These observations were supported by density functional theory (DFT) calculations. Compared to pure SnO₂, the doped SnO₂ demonstrated significantly higher photocatalytic activity, achieving an 88% degradation rate of rhodamine B after 150 min of irradiation—a 70% improvement over undoped SnO₂ (26%). This study highlights the potential of doped SnO₂ nanomaterials as efficient organic pollutant degraders in wastewater treatment.