Electrochemical Characterization of TiO2 Films Formed by Cathodic EPD in Aqueous Media

The present work studies the influence of applied electric field on the cathodic electrophoretic formation of TiO2 films in an aqueous medium. The growth of the film was followed by measuring current density, deposited mass, and thickness under imposed electric field (phi). In scanning electronic microscopy images of the TiO2 films formed under different electric fields, three regions can be seen: (i) formation of nuclei that are converted into agglomerates, (ii) uniform and one-sided growth, and (iii) growth by the formation of agglomerates on the TiO2 surface. The characterization of semiconductor properties showed that increased phi for film growth leads to an increase in the density of donors and to a displacement of the flatband potential toward less negative values. The photoelectrochemical characterization of the oxide films revealed that the photoelectrochemical performance of the TiO2 films decreases as a function of the electric field used to carry out the electrophoretic deposition (EPD) process. The electrochemical behavior observed for these films seems closely related to the content of Ti3+ doping sites electrogenerated in situ during the EPD, which act as electron traps negatively affecting the electron transport toward the indium tin oxide collector, also making their photoelectrochemical activity inefficient. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3208009] All rights reserved.