Ultrathin CuO nanowires grown by thermal oxidation of copper powders in air

• Ultrathin CuO nanowires were grown by thermal oxidation of Cu powders in air.
• The growth temperature and time are 300 °C and 1 h respectively.
• The diameters are distributed in the range of 5–10 nm.
• The photoluminescent properties are studied.

Copper powders were thermally treated in the air at a wide temperature range of 200–700 °C. It was found that thin CuO nanowires were grown at 300 °C and thick CuO nanowires were grown at 500 °C. The diameters of the thin CuO nanowires were distributed in the range of 5–10 nm, and the growth directions along [1̄11] and [110] were observed. In addition, the thermally treated copper powders with ultrathin CuO nanowires showed a broad violet emission band peaking at 402 nm.