Influence of Synthesis Temperature on <i>Catharanthus roseus</i> -Mediated CuO Nanoparticles for Improved Photocatalysis and Antibacterial Activity

This research presents an environmentally friendly green synthesis approach for copper oxide nanoparticles (CuO NPs) using an aqueous extract of Catharanthus roseus as both a reducing and capping agent. The study primarily focuses on systematically investigating the influence of different synthesis temperatures (30 ° C (C1), 60 ° C (C2), and 90 ° C (C3)) on the physicochemical and functional properties of the synthesized NPs. Detailed characterization through confirmed that crystalline, spherical CuO NPs with a monoclinic structure were successfully formed. The analysis indicated that variations in synthesis temperature significantly influenced the properties of the NPs; specifically, it showed that increasing temperature resulted in reduced crystallite size along with an expansion of the optical band gap. To evaluate their functionality, photocatalytic degradation tests involving methylene blue (MB) dye as well as antibacterial assays were conducted. Notably, the NPs synthesized at 60 ° C demonstrated enhanced photocatalytic activity. Conversely, the CuO NPs synthesized at 90 ° C exhibited the smallest crystallite size and enhanced antibacterial activity against both Gram-positive and Gram-negative bacteria. These results highlight temperature's crucial role as a modifiable factor during green synthesis processes for CuO NPs while establishing basil-mediated methods as a flexible and sustainable approach for generating high-performance nanomaterials suitable for environmental remediation efforts and biomedical applications.