OPTICAL AND PHOTOCATALYTIC PROPERTIES OF ELECTROSPUN ZnO FIBERS

ZnO nanofibers were obtained by electrospinning a solution of zinc acetate dihydrate and polyvinylpyrrolidone in N,N-dimethylformamide, followed by calcination at 500, 650 or 800 °C for 1 h. X-ray diffraction, selected area electron diffraction, scanning electron microscopy, transmission electron microscopy, reflectance spectroscopy and photoluminescence spectroscopy were used for the characterization of the resulting fibers. The thermally treated samples exhibit ZnO single phase with polycrystalline hexagonal structure. The morphological investigation revealed an accentuated contraction process during calcination, as well as the increase of the crystallite size and the appearance of a breaking tendency with the calcination temperature enhancement. Both UV and Visible emissions under excitation at 350 nm were showed by the optical studies, which also led to band gap values slightly lower than those reported for similar one-dimensional nanostructures. In order to assess the photocatalytic activity of ZnO fibers, the photodegradation of methylene blue in aqueous medium (10 -3 M) under UV irradiation (368 nm) was analyzed