Enhancement of photocatalytic activity of synthesized Cobalt doped Zinc Oxide nanoparticles under visible light irradiation

Abstract

Abstract In the present work, pure Zinc Oxide (ZnO) and Cobalt (Co) doped ZnO nanoparticles with various dopant concentrations are synthesized by chemical precipitation method. All the synthesized samples are subjected to characterization by different instrumentation tools such as X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra Violet–visible (UV–vis) absorption spectroscopy and Photoluminescence (PL) spectroscopy respectively. XRD results show the decrease in crystallite size of the synthesized samples with the increase of Co content. SEM image reveals that Co doping in ZnO results in change of the morphology of ZnO to nearly flower-like structures. The UV–vis absorption study shows that the energy band gap decreases as compared to pure ZnO with the increase of the content of Co dopant. PL spectra exhibit UV emission peak along with defect related visible emission. The intensity of visible emission reduces as the content of Co dopant increases. The photocatalytic activity of the synthesized samples is investigated for the degradation of Methylene Blue (MB) dye under visible light irradiation. The total organic carbon (TOC) analysis is done to evaluate the mineralization of the MB dye during photocatalytic process. Further, the effects of various parameters such as dopant concentration, catalyst dosage and initial concentration of the dye on the photocatalytic degradation process are extensively studied.