Biblioteca.

Abstract

ln this work some studies involving the electrodeposition of molybdenum oxide thin films from solutions containing Mo(VI) are reported. The influence of the concentration of Mo(VI) and the pH on the characteristics of the obtained film were evaluated by spectroscopic techniques and by analysing the electrocatalytic effect of the modified electrode on the response for the cathodic reduction of iodate ions. Similar experiments were carried out at solutions containing surfactants such as Triton X-100 and Brij 56 as an attempt to generate mesoporous structures. However, no experimental evidence on the f ormation of such structures were obtained and the good response of the modified electrode prepared in surf actant medium was attributed to the formation of thin films which posses better performance towards the electrocatalytic reduction of iodate. Results were compared with those obtained f rom working solutions in the absence of surfactants. The was based on the previous determination The results showed the influence of solution viscosity in the value of the diffusion coefficient of Some results on the use of microelectrodes to measure the diff usion coefficient of ferrocene supported CTAB micelles were also performed. By using a classical theory that predicts the interaction between micelles as a f unction of the surf actant concentration, the diffusion coefficient of CTAB micelles at conditions of non-interaction (Dº) and the hydrodynamic radius (Rº) of the CTAB micelle at this experimental condition were found to be 1. 7 x 10-6 cm 2 /s and 13 A, respectively, at 0.05 M KCI solutions. The effect of different anions (bromide, chloride and fluoride) on the micellar diffusion coefficient was investigated and changes in the structure of spherical CTAB micelles at higher ionic strength values were postulated based on analysis of micellar interaction coefficient vs. CTAB concentration plots.