A novel approach for the preparation of textured CuO thin films from electrodeposited CuCl and CuBr

We report on the electrodeposition of CuX (X = Cl, Br) thin films on fluorine-doped tin oxide (FTO) electrodes. The electrodeposited CuX thin films, for the first time, were used as intermediates to prepare CuO thin films. Calcination of the as-prepared CuX thin films at temperatures above 380 degrees C allowed us to produce CuO thin films, which were used in photoelectrochemical (PEC) studies. The highest recorded photocurrent density of similar to 1.3 mA/cm(2) at -0.55 V (vs. Ag/AgCl) in aqueous solution was obtained from the CuO sample calcined at 460 degrees C. Here, we showed that the photocurrent in the unprotected CuO electrode originates from corrosion, formation of Cu2O and Cu phases, and not from water-splitting process as it has been claimed in literature. In addition, the electrochemical impedance spectroscopy allowed us to obtain the flat-band potentials of the CuO films. (C) 2014 Elsevier B.V. All rights reserved.