Effect of ethylene glycol concentration on the structural and optical properties of multimetal oxide CdO–NiO–Fe2O3 nanocomposites for antibacterial activity

Abstract Herein, we present the effect of ethylene glycol (EG) concentration on the size of CdO–NiO–Fe2O3 nanocomposites with the intention to enhance their structural and optical properties for antibacterial activity. The self-combustion method was used to prepare trimetal oxide (TMO) nanocomposites. Structural and morphological properties of the prepared samples were studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Absorbance and photoluminescence (PL) spectra of TMO nanocomposites were investigated using a UV–visible spectrophotometer and PL spectroscopy. XRD measurements showed that CdO and NiO have a face-centered cubic structure, while Fe2O3 showed pure maghemite (γ-Fe2O3) phase with a cubic spinel crystalline structure. TEM measurements showed that the size of the TMO nanocomposites increased from about 9.4 to 20.8 nm as the EG concentration decreased from 1 M to 0.001 M. FTIR spectra showed the characteristics peaks for CdO, NiO, and γ-Fe2O3. Optical bandgap values of samples showed variation related to EG concentration due to the quantum confinement of TMO nanocomposites. Antibacterial activity of TMO nanocomposites was tested against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Moraxella catarrhalis) and Gram-positive bacteria (Staphylococcus aureus). It is the first time TMO nanocomposites have been tested against M. catarrhalis. The zones of inhibition of TMO nanocomposites were 13, 25, 25, and 25 mm for E. coli, P. aeruginosa, M. catarrhalis, and S. aureus, respectively. The enhanced ZOI of TMO nanocomposites makes them good candidates for antibiotic development.