Green synthesis of copper oxide nanoparticles using Euphorbia heterophylla leaf extract for deactivation of pathogenic bacteria and photocatalytic degradation of industrial dyes

• CuO NPs were green synthesized using phytochemicals present in Euphorbia heterophylla leaf extract. • With size range of 50 nm to 200 nm and mean size of 108 ± 0.2 nm, CuO NPs unveiled typical monoclinic crystal structure. • Substantial inhibition zones were observed for CuO NPs against Bacillus cereus and Escherichia coli bacterial strains. • Remarkable photocatalytic degradation efficiency against Congo red (93%) and Coomassie blue (99%) dyes was produced by CuO NPs. • Present findings underscore green synthesized CuO NPs potential for sustainable environmental remediation applications. Copper oxide nanoparticles (CuO NPs) were green synthesized using leaf extract of Euphorbia heterophylla ( E. heterophylla ). The synthesized CuO NPs were characterized by X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet–visible (UV-Vis) spectrophotometer to determine their crystallinity, morphology, elemental composition, functional groups and optical properties, respectively. The obtained CuO NPs exhibited monoclinic crystal structure and their particles size ranged from 50 nm to 200 nm with an average particle diameter of 108 ± 0.2 nm. The observed band gap energy of the CuO NPs was 1.49 eV. Antibacterial studies demonstrated significant inhibition zones of 34 mm, particularly against Bacillus cereus and Escherichia coli bacterial strains, which were 1.4-fold higher than the zone of inhibition (24 mm) exhibited by the standard antibiotic (tetracycline). During the photocatalytic studies, exposure to natural sunlight significantly enhanced degradation efficiency of the CuO NPs, resulting in the rapid degradation of Congo red (99%) and Coomassie blue (93%) dyes within just 40 min. The photocatalytic degradation rate constant for Congo red and Coomassie blue dyes was 13.92 × 10 –4 s –1 and 10.82 × 10 –4 s –1 , respectively. These findings highlight that the E. heterophylla leaf extract can provide a novel and eco-friendly route to synthesis CuO NPs that contributes to advancements in green nanotechnology. The effective antibacterial and photocatalytic activities of green synthesized CuO NPs emphasizes their potential for sustainable environmental remediation applications.