Tunable synthesis of cuprous and cupric oxide nanotubes from electrodeposited copper nanowires

Polycrystalline copper oxide nanostructures with different valence/oxidation states (i.e., Cu ₂O and CuO) were readily synthesized by thermal oxidation of single crystalline copper nanowires at relative low operating temperature (200 to 300 °C). Operating temperature of 200 to 250 °C in air oxidized copper to Cu ₂O and further increased temperature (i.e., 300 °C) led to form CuO nanostructures. The morphology of nanostructures significantly altered from nanowires to nanotubes which might be attributed to Kirkendall effect. The electrical resistivity of single copper nanowire, Cu ₂O and CuO nanotube were determined to be 3.4 × 10 ^-4, 33, and 211 Ω cm, respectively.