Synthesis, characterization and antibacterial activity of cobalt doped cerium oxide (CeO2:Co) nanoparticles by using hydrothermal method

Abstract

Different concentrations (2, 4, 6, and 8 mole %) of cobalt doped cerium oxide nanoparticles (CeO2:Co NPs) were synthesized by hydrothermal method. The synthesized samples were characterized by using various techniques to understand their structural, optical and surface morphological properties. The face-centred cubic (FCC) structure of the CeO2:Co NPs was identified from the X-ray diffraction (XRD) analysis. The calculated crystallites size of the CeO2:Co NPs were decreased from 20 nm to 17 nm on increased the concentration of cobalt from 2 mole % to 8 mole %. The bonding formation between cerium and oxygen (CeO) was confirmed using Fourier transform infra-red spectroscopy (FTIR). The surface morphology and shape of the CeO2:Co NPs were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM images have revealed a cube shaped, uniformly distributed and well dispersed CeO2:Co NPs. Further, a slight distortion of surface morphology was obtained when increased the concentration of cobalt. The optical properties were investigated by using ultra-violet visible (UV–vis) spectroscopy. A optical absorption band nature was observed from CeO2:Co NPs when compared with bulk spectrum. The bandgap energy of the CeO2:Co NPs were increased from 3.64 eV to 3.69 eV on increased the cobalt concentration. The photoluminescence (PL) emission spectrum of CeO2:Co NPs showed an enhanced defect of reduced emission by using spectrofluorometer. The CeO2:Co NPs resulted good antibacterial activity against pathogenic bacteria such Escherichia coli, Staphylococcus aureus, Bacillus Cereus and Salmonella Typhi. Hence, the CeO2:Co NPs could be used as biomaterial in nano-biotechnology applications. Keywords: Cerium oxide, Cobalt, Hydrothermal method, Cubic shape, Antibacterial activity