Sustainable Synthesis of Copper Oxide Nanoparticles: Data-Driven Photocatalysis, Pt-Free Hydrogen Production, and Antibacterial Assessment

This study reports the green synthesis of copper oxide nanoparticles (CuO NPs) using Oxystelma esculentum extract as a reducing and stabilizing agent. The state-of-the-art analysis confirmed their spherical morphology, with an average particle size ranging from 20 to 25 nm, while XRD indicated a crystalline structure consistent with the standard JCPDS card. The photocatalytic degradation of norfloxacin (NOR) was optimized using Response Surface Methodology (RSM), which identified the optimal conditions as a reaction time = 47.51 min, CuO-NPs dose = 48.46 mg, NOR dose = 35.90 ppm, and pH = 5.23. Under these optimized conditions, the CuO NPs achieved an initial degradation efficiency of 90%. In addition to photocatalytic degradation, the hydrogen (H₂) evolution performance of the CuO NPs was evaluated, yielding a H₂ production rate of 19.52 mmol g⁻¹ h⁻¹ under visible light. Moreover, the antimicrobial activity of the CuO NPs was assessed, showing significant antibacterial effects with inhibition zones of 8 mm and 9 mm against Klebsiella and Bacillus species. The CuO NPs also exhibited potent anticancer activity with an IC₅₀ value of 15.3 ± 1.40 μM against the HeLa cell line and notable antifungal activity with inhibition rates ranging from 70% to 90% against various fungal species.