Formation of CuO nanowires on Cu foil

We report the growth of CuO nanowires from copper foils oxidized in wet air at temperatures between 300 and 800 °C. Within the temperature range of 400–700 °C, the nanowires formed have two different morphologies, curved and straight, with diameters between 50 and 400 nm and lengths between 1 and 15 μm. The growth behavior can be understood in terms of kinetics involving short-circuit diffusion, the strength of the nanowires, and the thickness ratio of the oxide scale and the metal.