Green synthesis of Cu-doped ZnO nanocomposites using Phytolacca dodecandra root extract to improve photocatalytic and antibacterial activity and extend avocado shelf-life

Water pollution from industrial dyes and fruit spoilage due to microbes are significant global challenges. Solutions like photocatalytic degradation and preservation techniques are essential. Coating fruits with nanomaterials can reduce microbial contamination and extend shelf life, while these materials also provide alternatives against antibiotic-resistant bacteria. The primary objective of this study was to synthesize zinc oxide (ZnO) nanoparticles (NPs) and copper-doped ZnO (Cu-ZnO) nanocomposites (NCs) using Phytolacca dodecandra root extract as a natural reducing and stabilizing agent, enabling multiple applications such as photocatalysis, antibacterial activity, and preservation. The synthesis employed a green, coprecipitation method, optimizing parameters like precursor salts and deionized water as the solvent. The synthesized nanomaterials were thoroughly characterized through techniques including UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). UV-Vis analysis revealed energy band gaps of 3.21 eV for ZnO NPs and 2.76 eV for Cu-ZnO NCs, indicating enhanced photocatalytic potential upon copper doping. Photocatalytic tests demonstrated degradation efficiencies of 85.2% for ZnO NPs and 98.2% for Cu-ZnO NCs, with the latter also showing stable activity over time. Furthermore, antibacterial assessments against three common pathogens showed that Cu-ZnO NCs exhibited stronger antimicrobial activity than undoped ZnO NPs. Overall, this study provides novel insights into the high-performance capabilities of Cu-ZnO nanocomposites in photocatalysis, antibacterial applications, and shelf-life extension; achieved through minimal copper doping of ZnO nanoparticles.