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Hierarchical CuO microspheres have been successfully synthesized by chemical bath deposition, during which Cu(OH) 2 nanorobs firstly transform into CuO nanosheets and then these nanosheets spontaneously self-assemble to form CuO microspheres. Detailed characterization of the synthesized nanomaterials was performed utilizing X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV–Vis absorption spectra to study their crystalline phase, morphology and optical property. Additionally, photocatalytic performance of Cu(OH) 2 /CuO composite and pure CuO nanostructures was evaluated. Optical gaps of them are 2.75 eV and 1.33 eV respectively, showing a significant enhancement in the photocatalytic property in comparison with commercial CuO as demonstrated in photodegradation of methyl blue (MB). A growth mechanism for the formation of CuO nanostructure was also proposed. [ABSTRACT FROM AUTHOR]

Monoclinic nanostructured CuO films with star-like morphology on indium tin oxide (ITO)-coated glass substrates were successfully synthesized by electrodeposition method in acidic solution with the pH of 5.7. The as-synthesized films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis. The influence of different electrodeposition parameters and annealing temperature on the growth of CuO films were investigated. The results showed that the nanostructured CuO film was well-crystallized and electrodeposition voltage is the main factor to control its morphology. Moreover, good photocatalytic activity was exhibited and photo-degradation rate to methylene blue can reach 95%. Its optical energy band gap is 3.3 eV. The plausible growth mechanism for the formation of CuO film with star-like structure is also proposed for the first time. [ABSTRACT FROM AUTHOR]

Urchin-like hierarchical ZnO nanostructures consisting of cone-shaped nanorods have been successfully obtained by electrodeposition-hydrothermal method. The as prepared samples were characterized by FESEM, XRD, UV–vis, PL and photocatalytic test. We have studied the important influence of hydrothermal time on the structural, morphological and optical properties. In the FESEM images, the cone-shaped ZnO nanorods radiate from the center of the nanostructures forming a spherical urchin-like shape with a diameter of 5–10 µm. The average diameter and the length of the cone-shaped ZnO nanorods can be identified as 0.1–1 µm and 3–5 µm, respectively. In the PL spectra, a violet emission band at about 402 nm and two blue emission bands at about 446 nm and 465 nm can be observed at room temperature. In comparison with the others, urchin-like ZnO nanostructures prepared under 4 h showed enhanced photocatalytic performance. The enhanced photocatalytic activity of urchin-like ZnO nanostructures might be resulting from the higher concentration of surface oxygen vacancies. [ABSTRACT FROM AUTHOR]