Journal of Sol-Gel Science and Technology, 2024 (SCI-Expanded)
This paper presents the antibacterial and antifungal activities of Ag/GO, Co3O4/GO, and ZnO/GO nanocomposites prepared using Moringa oleifera. The composite nature of the materials was confirmed due to the presence of principal peaks of GO, Ag, Co3O4 and ZnO in the UV–visible absorption spectra at 230, 420, 315, and 380 nm, respectively. The absorption data was further analyzed to estimate the bandgap energy of the nanocomposites. The formation of ZnO and Co3O4 in the GO nanocomposites was also verified due to the appearance of Zn–O and Co–O bands in FTIR spectra. However, the absence of Ag–O band in FTIR analysis further verified the formation of only Ag in the Ag/GO nanocomposite. The X-ray diffraction (XRD) analysis also revealed the existence of preferential diffractions due to hexagonal ZnO and cubic Ag and Co3O4 in the XRD patterns of GO nanocomposites. Moreover, the average crystallite sizes were found to be 53.10, 84.05, and 86.41 nm for ZnO/GO, Ag/GO, and Co3O4/GO nanocomposites, respectively. The crystallite size of GO content was noticed 18.39, 27.58, and 44.14 nm in Co3O4/GO, ZnO/GO, and Ag/GO nanocomposites, respectively. This increase in GO crystallite size was also correlated with the decrease in bandgap energy of Co3O4/GO (2.77 eV), ZnO/GO (2.62 eV) and Ag/GO (2.42 eV) nanocomposites, respectively. Thermal study revealed the higher stability of ZnO/GO nanocomposite in comparison to Co3O4/GO and Ag/GO nanocomposites. The different surface morphologies were noticed in scanning electron micrographs of the nanocomposites. Moreover, the antibacterial and antifungal activity studies demonstrated higher activity posed by ZnO/GO nanocomposite than Ag/GO and Co3O4/GO while using five Gram-positive bacteria, eleven strains of Gram-negative and six filamentous fungi.