Structural and optical characteristics, and bacterial decolonization studies on non-reactive RF sputtered Cu–ZnO@ graphene based nanoparticles thin films

Graphene oxide (GO) belongs to carbon family with honeycomb structure having hydroxide, carbonyl, and carboxylic moieties at its basal plane. These functionalities are decreased in reduced graphene oxide (rGO), and this boosts the intrinsic properties of GO. Herein, in this work, the effect on physical and chemical properties of GO and rGO in combination with copper-doped zinc oxide (Cu–ZnO) thin films, prepared via DC/RF sputtering, was investigated for the very first time. The deposition of Cu–ZnO over rGO (Cu–ZnO@rGO) showed remarkably superior properties and presented an extension in d-spacing without preferred plane orientation of Cu–ZnO plane, and this was found to be due to its hydrophobic nature. The decrease in band gap of composite thin films was due to the surface electric charge conducted by GO or rGO. The enhanced dielectric constant is attributed due to increase in electron–hole pairs owing to the increase in sp2 hybridization. However, sp2 network was also found to be responsible to provide the conductivity path way which increases the dielectric loss in Cu–ZnO@rGO thin films as compared to that in Cu–ZnO@GO; this might be due to aggregation of Cu–ZnO nanoparticles over the rGO films in comparison with GO as evident from the morphological analysis by AFM. The change in surface chemistry was ascribed with the ratio of COOH, C=O, C–OH and C–C bonding in the Cu–ZnO@GO and Cu–ZnO@rGO thin films as unveiled in their XPS analysis. The developed thin films exhibited enhanced antimicrobial activity against E. coli and E. faecalis which might be due to the synergistic effects of Cu–ZnO with GO or rGO.