Fabrication of single phase CuO nanowires and effect of electric field on their growth and investigation of their photocatalytic properties

Single phase CuO nanowires were grown at a large scale via thermal oxidation of a Cu substrate in air at 500 °C for several times. Usually during the oxidation process, a layer of Cu2O is grown on the surface of the substrate. Our results showed that by further annealing of the CuO (nanowires)/Cu2O layer, isolated from the Cu substrate, it is possible to convert the Cu2O to CuO nanowires. It was found that the Cu ion diffusion through the grain boundaries is the dominant growth mechanism in the thermal oxidation method. Also, effects of applying an electric field on the growth of nanowires have been investigated and it was found that the annealing in the electric field caused an increase in the concentration and uniformity of nanowires diameter. Also the adhesion of the CuO nanowires layer on the Cu substrate was observed. The photocatalytic activities of CuO nanowires were examined by photocatalytic degradation of Methyl Orange and Bromocresol Green dyes. The results showed that the nanowires grown at 500 °C had the best photocatalytic performance on both dyes.