Green synthesis of zinc oxide nanoparticles using two saffron flower extracts and their comparative photocatalytic efficiency in organic dye degradation

Abstract Zinc oxide (ZnO) nanoparticles are widely explored for photocatalytic degradation of organic pollutants due to their high stability, low cost, and environmental compatibility. In this study, ZnO nanoparticles were synthesized through two green routes using saffron (Crocus sativus) floral extracts to evaluate the effect of extract type and synthesis method on the structural properties and photocatalytic activity. Both saffron anther extract (Z2) and saffron petal extract (Z4) were utilized in the same co-precipitation method to produce green zinc oxide nanoparticles Z2 and Z4. Both approaches avoided toxic reagents, promoting sustainable nanomaterial fabrication. The samples were characterized using X-ray diffraction (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS), confirming the presence of crystalline ZnO with high purity and a nanoscale morphology. Photocatalytic activities were tested under direct natural sunlight using methylene blue (MB), rhodamine B (RhB), and crystal violet (CV) as model dyes. The results revealed that the synthesis route and type of extract significantly influenced degradation performance, with each sample showing dye-dependent activity. The variation in photocatalytic performance between samples synthesized using anther and petal extracts is attributed to differences in phytochemical composition, which influence nucleation behavior and the formation of surface defects. These findings demonstrate the potential of saffron-extract-mediated green synthesis to produce efficient ZnO photocatalysts for environmental remediation. Graphical Abstract