Morphology and photoluminescence of nanostructured oxides grown by copper passivation in aqueous potassium hydroxide solution

Copper foil was anodized in 1 M KOH at potentials ranging from -400 to -100 mV vs. Ag vertical bar AgCl electrode. Cyclic voltammetry showed a distinct peak with a maximum at around -150 mV. For anodizing at -100 and -200 mV, nanowires with diameters of ca. 19 and 24 nm respectively were found to be grown. Moreover, photoluminescence and X-ray diffraction show that the dominant phase is the CuO phase. At lower potentials, cuboidal micron sized crystals were formed and Cu2O was found to be the major phase. (C) 2017 Elsevier B.V. All rights reserved.