Selective fabrication of Cu/Cu2O nanowires using porous alumina membranes in acidic solution

Cu/Cu2O nanowires were synthesized using anodic aluminum oxide templates in an aqueous acidic electrolyte using alternating current electrochemical deposition. The features of the final product were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). The results indicated that the diameter of the nanowires is about 50 nm, which is in accord with the size of the pores in the anodic aluminum oxide templates. The crystalline structure of the Cu and Cu2O nanowires exhibit preferred orientations of Cu (111) and Cu2O (200). respectively. The experimental results showed that contents of Cu and Cu2O in the final product are controlled by changing the pH value of the electrolyte. Pure Cu nanowires were obtained at lower pH values of 1-3, while pure Cu2O nanowires formed at a higher pH value of 5. When the pH = 4, the nanowires produced were a composite of Cu and Cu2O. The growth of Cu2O nanowires in acidic electrolyte is ascribed to a local increase in pH at the base of the pores in the template and a phenomenological model for this process is proposed and discussed. (C) 2010 Elsevier Masson SAS. All rights reserved.