Green synthesis of silver nanoparticles using Solanum lycopersicum leaves extract for highly selective detection of mercury ions and photocatalytic degradation of methylene blue.

This study reports the green synthesis of silver nanoparticles (AgNPs) using Solanum lycopersicum var. cerasiforme (SLC) leaves extract as a natural reducing and stabilizing agent under direct sunlight for just only 3 min. The main objective was to develop a rapid, cost-effective, and environmentally friendly method to fabricate SLC-functionalized AgNPs (SLC-AgNPs) for dual applications: highly selective colorimetric detection of mercury ions (Hg2⁺) and photocatalytic degradation of methylene blue (MB) dye. The synthesized nanoparticles were characterized by UV-Vis, FTIR, XRD, SEM, EDX, and DLS, confirming their spherical shape (~ 38 nm), crystalline structure, and stable surface functionalization. The SLC-AgNPs exhibited exceptional selectivity for Hg2⁺ through a redox reaction mechanism, enabling colorimetric sensing with a low detection limit of 37.7 nM and a linear response range of 40-180 nM. Detection of Hg2⁺ in real river and tap water samples validated the sensor's practical applicability, with recoveries above 85%. In addition to sensing, the SLC-AgNPs demonstrated significant photocatalytic efficiency, degrading 83.4% of MB dye within 80 min of sunlight exposure, following pseudo-first-order kinetics with an activation energy of 35.02 kJ/mol. This dual- functionality capability highlights the novelty of the green synthesized SLC-AgNPs as an eco-friendly nanomaterial that combines sensitive heavy metal detection with effective dye degradation. These findings suggest promising potential for SLC-AgNPs in sustainable environmental monitoring and wastewater treatment, bridging cost-efficiency with high-performance nanotechnology.