Cu2O:  Electrodeposition and Characterization

Well-defined polycrystalline Cu2O was electrodeposited on transparent conducting substrates from alkaline Cu(II) lactate solutions. The morphology of the layers could be controlled by choosing the appropriate experimental conditions; the pH and temperature of the deposition solution were especially important. The growth of the oxide involves a thermally activated process, for which an activation energy of 0.8 eV was found. A mechanism for the deposition is proposed. The optical absorption of the electrodeposited oxide in the visible range was much weaker than expected for a direct semiconductor with a band gap of 2.0 eV. Finally, we show that it is possible to grow Cu2O inside an n-type TiO2 nanoporous matrix.