rGO/Ag-SnO₂ nanocomposites: Facile synthesis and enhanced photocatalytic and antibacterial performance

The removal of organic contaminants from wastewater remains a major environmental concern. In this study, rGO/Ag-SnO₂ nanocomposites (RAS NCs) were synthesized using a simple sol-gel route followed by room-temperature treatment to enhance photocatalytic and antibacterial performance under visible light. Optical analysis showed a reduction in band-gap energy from 3.22 eV for pure SnO₂ to 2.62 eV after the incorporation of Ag and rGO, resulting in improved light absorption. Structural and morphological investigations confirmed the successful formation of the composite with Ag-SnO₂ nanoparticles uniformly dispersed on rGO sheets. Among the prepared materials, the sample containing 6 wt% rGO exhibited the highest activity, achieving 95.02% degradation of Brilliant Green dye under solar irradiation, compared with 29.52% for pristine SnO₂. The degradation process followed pseudo-first-order kinetics with a rate constant of 0.02142 min⁻¹ and a half-life of 32.35 min. The enhanced performance was attributed to the synergistic role of Ag and rGO in facilitating charge separation and electron transport while suppressing charge recombination. Furthermore, the optimized nanocomposite demonstrated good stability and reusability during repeated cycles. Significant antibacterial activity was also observed against Escherichia coli (18 mm), Proteus sp (15 mm), Staphylococcus aureus (17 mm), and Bacillus sp (15 mm). Overall, the developed RAS NCs show considerable potential as multifunctional materials for wastewater purification and antimicrobial applications.