Improved photocatalytic properties and anti-bacterial activity of size reduced ZnO nanoparticles via PEG-assisted precipitation route

ZnO nanoparticles have been prepared by precipitation method with different concentrations of polyethylene glycol-6000 (PEG-6000) as capping agent. Present work highlighted that by increasing the concentration of the PEG-6000 the crystalline size can be reduced from 31 to 25 nm. It was also observed that capping agent greatly influences the morphology of ZnO nanoparticles. UV–Vis absorption spectroscopy results reveal that due to quantum confinement effect the capping of PEG-6000 with ZnO leads to blue shift which have also been corroborated by photoluminescence studies. Further, FTIR and Raman spectra evidence the presence of several modes of ZnO which further confirms the good optical quality and wurtzite hexagonal phase of the grown nanostructures. Moreover, photocatalytic tests of the PEG-capped ZnO nanoparticles for the degradation of the methyl green dye revealed extremely high photocatalytic activity compared with those of bare ZnO nanoparticles. The remarkable photocatalytic performances of PEG-capped ZnO nanoparticles were mainly due to the high concentration of surface defects. Furthermore, the PEG capped ZnO nanoparticles significantly inhibited the growth of medically important pathogenic gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli) in comparison with the bare ZnO nanoparticles.