Structural elucidation and spectral characterizations of Co3O4 nanoflakes

• The size of these nanoparticles is in the range of ∼10–20 nm.
• B.E., at 780.0 and 796.2 eV, corresponding to Co 2p3/2 and Co 2p1/2, respectively.
• The strong peaks of CO as well as O and confirms the presence of CO in the product.
• Linearly fitted into two lines with the intercept at 2.28 and 1.57 eV.
• The peak at 2506 cm−1 pertaining to Co2 is vibrant by environmental effect.

A facile solvothermal process is successfully developed to prepare F-center cubic Co3O4 nanoflakes in ethylene–glycol–water solvent. Cobalt acetate [Co(Ac)2⋅4H2O] is directly used as precursor and ethylene glycol performs a reducer and modifying agent in the system. The as obtained products were characterized by XRD, FT-IR, UV–Vis-DRS, SEM, EDAX, XPS and HR-TEM. XRD studies indicate that the nanoflakes have the same crystal structure found in cubic form of Co3O4. The lattice parameter, X-ray density and the specific area of nanoflakes were also estimated from XRD pattern. The various functional groups present in Co3O4 nanoflakes were identified by FTIR analysis. The band gap energy of Co3O4 nanoflakes was calculated from UV–Vis-DRS spectral studies. SEM analyses ascertain that Co3O4 nanocrystals are nanoflakes in nature and the particle size in SEM is exactly consistent with XRD results. The elemental composition was determined using the energy dispersive X-ray spectroscopy was performed at several points in the region and averaged to obtain the representative results. The atomic composition of the Co3O4 was detected by X-ray photoelectron spectroscopy (XPS). The nanoscale structures were observed using high-resolution transmission electron microscopy.

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