Impact of graphene oxide integration with ZnO nanoparticles on its photocatalytic, antimicrobial, and antioxidant activities

Zinc oxide nanoparticles (ZnO-NPs) are a type of nanomaterial that is biodegradable and has low toxicity and high compatibility with biological systems. They appear to have great potential for biomedical and photocatalysis applications, especially when compared to other metal oxide nanomaterials. Moreover, ZnO-NPs exhibit strong ultraviolet (UV) absorption properties, are cost-effective, and are easy to synthesize. However, pure ZnO-NPs have several limitations, including a wide energy bandgap, high excitation binding energy, poor photocatalytic activity in the visible range, and significant electron-hole recombination, which restrict their applications. To address these limitations, this study successfully incorporated graphene oxide (GO) into ZnO-NPs. Adding 4% GO reduced the energy band gap from 2.87 eV to 2.20 eV, significantly enhancing their activities. As a result of the integration, their photocatalytic activity enhanced, degrading 98% of methylene blue dye after 80 minutes of visible light exposure. Furthermore, GO incorporation boosted their antioxidant activity, increasing their half-maximal inhibitory concentrations (IC50) from 38.38% to 51.60%. The nanocomposite exhibited superior antimicrobial activity compared to the pure ZnO-NPs and GO, indicating enhanced antimicrobial effects through GO integration. These enhancements are attributed to the improved band gap, stability, surface functionality, and nanocomposite morphology, as confirmed by various characterization methods. KEY WORDS: Antimicrobial, Antioxidant, Dye degradation, GO/ZnO nanocomposite, Reactive oxygen species. Bull. Chem. Soc. Ethiop. 2025, 39(3), 515-534. DOI: https://dx.doi.org/10.4314/bcse.v39i3.10