¹ Department of Chemistry, Minhaj University, Lahore, Pakistan

² Renewable Energy and Environmental Technology Center, University of Tabuk, Tabuk, 47913, Saudi Arabia

³ School of Chemistry, University of the Punjab, Lahore 54590, Pakistan

⁴ Department of Basic Sciences (Section Biochemistry), University of Veterinary and Animal Sciences Lahore (Jhang Campus), Jhang, Pakistan

⁵ Institute of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Pakistan

⁶ Department of Physics, College of Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia

⁷ Department of Chemistry, The University of Lahore, Lahore, Pakistan

* Correspondence: nmalwadai@pnu.edu.sa

Copper-doped zinc oxide nanoparticles (Cu-d-ZnO NPs) were prepared via a precipitation-dispersion method with different copper concentrations (1–5%) and the structural, photocatalytic and antimicrobial properties were studied. XRD analysis revealed that ZnO has a hexagonal structure with a decrease in particle size with increasing copper content. The average crystallite sizes were found to be 27.8±2.0 nm, 24.6±1.6 nm and 21.9±1.7 nm for 1%, 3% and 5% Cu-doped ZnO samples, respectively. The morphology analysis revealed a porous structure with cluster aggregate formation of the NPs and EDX analysis revealed the presence of Zn, Cu and O elements. Thermal analysis revealed that ZnO NPs have good thermal stability up to 900 °C with 9.16-29.31% mass loss. Photocatalytic activity against methylene blue (MB) dye was carried out under UV light irradiation and it was found that 85.5% removal was achieved for Cu (5%)-d-ZnO NPs, whereas ZnO furnished 58% efficiency. Results of the antimicrobial study against S. aureus, B. subtilis, E. coli and P. multocida indicated 30% enhanced activity of Cu-d-ZnO as compared to pure ZnO. The minimum inhibitory concentration of Cu-d-ZnO against bacteria was found to be 178–354 µg/mL, whereas against fungi (A. flavus, A. niger and P. notatum), the values of the minimum inhibitory concentration of Cu-d-ZnO were found to be 286–407 µg/mL. Scavenger studies revealed that photogenerated electrons play a crucial role in initiating reactive oxygen species formation through reduction of dissolved oxygen to superoxide radicals (O₂^•⁻), while hydroxyl radicals (^•OH), generated via hole-mediated oxidation of water and hydroxyl ions, act as the primary oxidizing species responsible for dye degradation. These findings demonstrate that Cu doping enhances charge separation and reactive oxygen species generation, thereby improving photocatalytic efficiency. These results indicate the potential of Cu-d-ZnO NP to be used for the remediation of dyes as well as for the treatment of infections. The Cu-d-ZnO NPs show strong potential for applications in dye remediation and antimicrobial treatment. Future work should focus on optimizing operational parameters and evaluating toxicity and environmental safety for practical applications.