Organic free synthesis of flower-like hierarchical CuO microspheres by reflux condensation approach

In the present work, CuO nanostructures with different morphologies were synthesized by a simple one-pot reflux condensation approach using different alkaline precursors. Structural analysis by X-ray diffraction and Fourier transform infrared spectroscopy revealed the formation of single phase CuO with a monoclinic crystal structure. Morphological analysis by scanning electron microscopy showed the formation of spindle-shaped and flower-like CuO architecture when NaOH and NH4OH were used as alkaline precursors, respectively. The flower-like CuO architecture is found to be made up of 2D nanosheets as building blocks, which were self-assembled to form spherical assemblies. Optical analysis by UV-VIS diffused reflectance spectroscopy showed blue-shift in the optical band gap due to quantum confinement effect. Photoluminescence spectra showed both UV and visible emission. The plausible growth mechanism for the formation of different CuO nanostructures was proposed.