Morphological, structural, and photoelectrochemical characterization of n-type Cu2O thin films obtained by electrodeposition.

Thin films of copper(I) oxide (Cu2O) were electrodeposited on fluorine-doped tin oxide predeposited glass substrates, by reduction of Cu2+ from Cu(II) acetate acid aqueous solutions. The Cu2O was potentiostatically grown at a potential value of −0.450 V (vs. SMSE) at 70 °C. The Cu2O thin films were characterized by means of scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), optical transmission, electrochemical impedance spectroscopy, and photoelectrochemical experiments. Through these techniques, it was possible to establish the cubic Cu2O phase with a high crystallinity and a strong preferential growth along the [200] and [220] directions. Cu2O thin films show oxygen vacancies with formation of a nonstoichiometric compound with the presence of Cu(0) in the crystal lattice as determined by XPS analysis. In addition, Cu2O was used as the photoanode for the I− oxidation reaction when the system was illuminated ( Φ0 = 50.0 mW cm−2). The films exhibited a clear n-type semiconductor behavior, which was in agreement with the Mott-Schottky results. This behavior was explained by considering the nonstoichiometry of the oxide. [ABSTRACT FROM AUTHOR]