CuO nanowires synthesized by thermal oxidation route

CuO nanowires were prepared on the copper foil by thermal oxidation in air. The effect of annealing temperature and growth time on the morphology of the nanowires is investigated. It is found that the annealing temperature and the growth time play an important role in the morphology of CuO nanowires such as the density, the length and the diameter. The length and the density of nanowires increase with prolonging growth time; but if the time is too long, CuO crystallite grains form instead of nanowires. Annealing copper foils at lower or higher temperature, the density of nanowires is lower. For comparison, the Cu films on Si substrate deposited by direct current (dc) magnetron sputtering are oxidized, but we do not find large-scale of nanowires. The possible mechanism is also discussed for the growth of CuO nanowires.