Green sonochemical synthesis of cupric and cuprous oxides nanoparticles and their optical properties

Nanoparticles of cupric oxide (CuO) and cuprous oxide (Cu2O) with various morphologies were synthesized by a green sonochemical process without any surfactants and templates. The Cu2O nanoparticles with the truncated cubic, cubic octahedral and octahedral morphologies were prepared via the deoxidation of the CuO nanoparticles. The Cu2O and CuO samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible absorption spectroscopy (UV-vis). The experimental results indicate that the molar ratio of sodium hydroxide to copper sulfate affects the morphology and size of the CuO and Cu2O nanoparticles produced by the sonication. The band gap energy of CuO nanoparticles was 1.45-1.75 eV, the morphology had a great effect on the optical properties of CuO. The Cu2O nanoparticles had broad emission peaks at the visible region, and the band gap energy was estimated to be 1.95-2.09 eV. The growth mechanisms of the CuO and Cu2O nanoparticles are discussed.