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

Abstract

Abstract Thin films of copper(I) oxide (Cu 2 O) were electrodeposited on fluorine‐doped tin oxide predeposited glass substrates, by reduction of Cu 2+ from Cu(II) acetate acid aqueous solutions. The Cu 2 O was potentiostatically grown at a potential value of −0.450 V (vs. SMSE) at 70 °C. The Cu 2 O 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 Cu 2 O phase with a high crystallinity and a strong preferential growth along the [200] and [220] directions. Cu 2 O 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, Cu 2 O was used as the photoanode for the I − oxidation reaction when the system was illuminated ( Φ 0 = 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.