Bio-fabrication of tin oxide (SnO₂) nanoparticles Capped with rosmarinic acid in Argument with antimicrobial activity and photocatalytic degradation

This investigation emphasizes the green synthesis and economical method of SnO₂-NPs using crude rosmarinic extract via ultrasonic-assisted extraction methodology. The leaf extract acts as an excellent reducing, capping, and stabilizing agent for SnO₂ preparation. The morphology, elemental conformation, crystallinity, size and functional groups responsible for surface stabilization and capping of as-synthesized SnO₂ nanoparticles, were characterized. UV absorption showed absorption peak of 200 nm with energy band gap of 2.23 eV and the functional groups recorded in the range of 400 to 4000 cm⁻¹ defined SnO₂ formation. The crystalline nature was confirmed via XRD, and both the element peaks (Sn and O) are observed through EDX analysis. The irregular spherical shapes of 6–18 nm are evaluated via TEM and SEM. SAED confirmed the nanocrystalline nature. The green synthesized SnO₂ nanocomposite demonstrated excellent methylene blue photocatalytic efficiency, and the subsequent potential mechanism was proposed. Utilizing this nanocomposite, nearly 89.79 % of Methylene Blue was removed in 80 mins under direct sunlight, documenting it as an efficient photocatalyst. Furthermore, the nanocomposite demonstrated comparable antimicrobial activity towards Escherichia coli and Klebsiella pneumoniae, illustrating the effectiveness of the nanocomposite. Consequently, the current work explains the significant synthesis of SnO₂ nanoparticles and demonstrates their potential photocatalytic and antibacterial properties.