Synthesis on large area and uniform nanosheet morphology of polycrystalline cobalt oxide Co3O4 obtained from oxidation of Co films in a pure oxygen atmosphere

Large area and uniform nanosheets Co₃O₄ have been fabricated by thermal annealing of cobalt thin film under the DC magnetron sputtering method. The synthesis is based on controlling the simple thermal oxidative formation of precursor Co films. The Co films were heated at 300, 400, and 500 °C for two hours in a pure oxygen atmosphere. At 300 °C, CoO and Co₃O₄ phases appear to survive together. An amount of pure polycrystalline Co₃O₄ nanosheets were observed at 400 °C. The structural and morphological properties of the nanosheets Co₃O₄ were characterized by means of transmission electron microscopy (TEM) and Raman spectroscopy.