Nanostructuring of anodic copper oxides in fluoride-containing ethylene glycol media

We demonstrate that the anodization of copper in alkaline water/ethylene glycol media containing fluoride ions generates nanostructured copper oxide films. By modifying the anodization conditions (fluoride and OH- concentrations, applied voltage and anodization time), nanoflbrillar Cu2O as well as highly rough nanofibrillar network or nanoporous mixed Cu2O/CuO films are obtained. Raman and X-ray Photoemission Spectroscopy (XPS) results indicate that in fluoride presence, Cu(I) oxide is obtained when anodization takes place applying low voltages at a relatively low OH- concentration. In comparison, the subsequent oxidation to obtain Cu(II) species (CuO and Cu(OH)(2)) is promoted by increasing the OH- contents. According to the present results, an oxidation reaction scheme is proposed in order to gain a deeper understanding in the preparation of controlled nanostructured copper oxide films.