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The present work studies the influence of applied electric field on the cathodic electrophoretic formation of TiO 2 films in an aqueous medium. The growth of the film was followed by measuring current density, deposited mass, and thickness under imposed electric field ͑͒. In scanning electronic microscopy images of the TiO 2 films formed under different electric fields, three regions can be seen: ͑i͒ formation of nuclei that are converted into agglomerates, ͑ii͒ uniform and one-sided growth, and ͑iii͒ growth by the formation of agglomerates on the TiO 2 surface. The characterization of semiconductor properties showed that increased 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 TiO 2 films decreases as a function of the electric field used to carry out the electrophoretic deposition ͑EPD͒ process. The electrochemical behavior observed for these films seems closely related to the content of Ti 3+ 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.TiO 2 is the material that has been most frequently employed in photoelectrochemical cells because of its unique properties, such as high stability, high photocatalytic activity, and relatively low cost. 1-14 However, TiO 2 is generally found as a particulate material and requires processing for the formation of a film that allows its application in photoelectrochemical cells ͑with stability, high surface area, and good activity͒. Among different techniques proposed in the literature for the preparation of these films, the best for its application on an industrial scale, due to its relatively low cost and good reproducibility, is the electrophoretic deposition ͑EPD͒. 15 Although it has not been extensively employed in the preparation of photoanodes, the results achieved so far using this technique are promising and prove that semiconductive oxide films can be easily prepared from stable colloidal suspensions that exhibit good stability and photoelectrochemical performance. 7,8 The EPD technique is feasible for the preparation of films of different semiconductive materials; for instance, Kim et al. 6 employed EPD in the fabrication of solar cells with TiO 2 nanotubes and obtained a solar energy performance 6.72% higher than that achieved using the doctor blade method, whose efficiency was just 0.65%. The EPD has also been useful in the preparation of films made of composed materials, such as TiO 2 /PTh, 12 TiO 2 /C, 2 and TiO 2 nanotubes modified with WO 3 . 5 Likewise, it has been used to characterize the photoelectrochemical properties of materials such as WS 2 , SnS 2 , 16 and K 4 Nb 6 O 17 . 17 One important characteristic of the EPD is that it has different operating variables that allow al...

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The effect of different electrolytes ͑ClO 4 − , NO 3 − , and SO 4 2− at 1 M͒ at pH 3 on the kinetics, growth type, and morphology of copper electrodeposition on glassy carbon was studied. The concentration was 0.1 M Cu 2+ in all of the solutions employed. In cyclic voltammetry, a larger reduction peak was obtained in the nitrate electrolyte, in comparison with the other two media. This higher current has been associated with the catalytic reduction of nitrate ions on recently deposited metallic copper. This effect was confirmed in the potential-step analysis. Despite the fact that Cu + is not thermodynamically stable in these three solutions, the reduction step Cu 2+ /Cu + has been considered as an electron-transfer reaction. The anion type has a direct effect on this electrontransfer reaction and consequently, on the electrocrystallization process; sulfates provoke the most important current decrease associated with the Cu 2+ /Cu + step and also strongly influence the nuclei formation, while the nitrate ions accelerate the Cu 2+ /Cu + step. The scanning electron microscopy images obtained for copper deposits after different deposition times corroborate the type of copper nucleation predicted by the electrochemical techniques.

In this work we report the synthesis and physical properties (thermal stability, diffraction patterns, and conductivity measurements) of a methacrylate-type polymer with zwitterionic pendant groups. The parent polymer, poly(sulfobutylbetaine of 12-ethyl-3,6,9-trioxa-12-azatetradec-1-yl 2-methylacrylate) (herein labeled PMBS-4) is used to prepare polymer/lithium salt complexes (PMBS-4/LiCl, PMBS-4/Li-triflate, and PMBS-4/LiClO 4 ). The resulting electrolyte polymers show mechanical properties akin to elastic solids. The glass transition temperature is close to 20 °C for all specimens, and PMBS-4/LiCl is thermally stable up to 187 °C. The conductivity of these materials varies with temperature, following an Arrhenius-like relationship. The conductivity of the solid polymer electrolytes, SPE, follows the order PMBS-4/LiClO 4 > PMBS-4/LiCl > PMBS-4/Li-triflate. The ionic conductivity of these materials is clearly affected by the anion of Li salt.