Enhanced photocatalytic degradation of rhodamine B dye (RhB), fluorescein dye (Flu), and their mixture using AgI/SnO₂ photocatalyst

AgI/SnO₂ composites, synthesized via sol–gel method, emerge as highly efficient photocatalysts for degrading rhodamine B (RhB), fluorescein (Flu), and their mixtures, shifting photocatalytic activity into the visible spectrum. Characterized by XRD, FESEM, DRS, EDX, mapping, TEM, BET, and XPS, these nanocomposites, especially with 15% AgI, show a remarkable increase in photocatalytic efficiency for Flu, achieving a rate constant of 0.0189 min⁻¹ which is triple that of pure SnO₂ at 0.0061 min⁻¹. The optimal degradation of Flu, RhB, and their mixture occurs with 0.1 g of the 15 wt% AgI/SnO₂ composite. This enhancement is attributed to the Z-scheme mechanism facilitated by the small energy gap between AgI and SnO₂ conduction bands, effectively minimizing electron–hole recombination and boosting photocatalytic performance through the generation of superoxide and hydroxyl radicals. These findings position AgI/SnO₂ composites as promising candidates for treating both cationic and anionic dye pollutants.