Structural and optical modulation of SnO₂ via Ba doping for superior visible-light photocatalytic performance

This study employs barium doping as a modification strategy to investigate the structural, optical, and photocatalytic properties of tin dioxide nanoparticles synthesized via the co-precipitation method, with a particular focus on the visible-light-driven degradation of methylene blue. XRD confirmed the tetragonal cassiterite structure of SnO₂ was retained upon Ba incorporation, with lattice distortion and peak broadening indicating successful substitution of Ba²⁺ into the SnO₂ lattice. FESEM analysis revealed a notable morphological evolution from spherical aggregates in pure SnO₂ to well-defined nanorod-like structures with increasing Ba concentration. In this study, the band gap of pure SnO₂ was measured to be 3.81 eV, which decreased to 3.70 eV for 0.075 M Ba@SnO₂, while PL spectroscopy confirmed the suppression of electron–hole recombination in this material. The photocatalytic degradation of MB under visible light irradiation increased significantly from 38% for pure SnO₂ to 56% and 79% for 0.05 M and 0.075 M Ba@SnO₂, respectively, following pseudo-first-order kinetics. The enhanced performance is attributed to synergistic effects of bandgap engineering, defect-induced charge trapping, and morphological modification. These findings establish Ba doping as an effective and scalable strategy for optimizing SnO₂-based photocatalysts for environmental remediation applications.