CONSTRUÇÃO DE ÂNODOS DIMENSIONALMENTE ESTÁVEIS (DSA) DE BAIXO CUSTO UTILIZANDO PbO2

Abstract

In the present study, an investigation was made about the effects of additives on PbO2 films using Platinum and Titanium as substrates. Platinum was used in order to eliminate a possible Titanium oxide interference, which is formed together Lead dioxide when Titanium is used as substrate. There were performed Cyclic Voltammetry, Electrochemical Impedance Spectroscopy, Mott-Schottky curves, Tafel curves, UV-Vis spectroscopy, X-Ray Diffraction, and Scanning Electron Microscopy experiments on PbO2 electrodes with and without Fe3+ and F- doping, besides a lamellar material of vanadium oxide and F-. The study demonstrated that should be considered that the real surface area of the electrode may change with the porosity leading to wrong conclusions about catalytic activity of the electrode, which is proportional to current density. The incorporation of these additives modified film nucleation and growth, which led to changes on morphology and consequently modifies materials area. In this paper, it could be verified the additives don’t change PbO2 semiconducting properties, in contrast to other reports. However, in experiments using Titanium as substrate, it was observed the occurrence of different inclinations on Mott-Schottky curves, showing the electronic parameters of TiO2 was changed. Thus, it was proposed that additives could be causing modification on electronic properties of Titanium dioxide film, that is present when Titanium is used as substrate. In this way, it is suggested that modifications on electrocatalytic properties of the electrode with additives could be caused by morphological changes and, possibly, by adsorption of additives to the electrode, which can cause surface modifications, or changes on electronic properties of TiO2 film. Furthermore, it was demonstrated that PbO2 deposition on Titanium occurs in specific crystallographic orientations, as already cited by literature. Thus, the actual need of forming an intermediate layer between Titanium substrate and PbO2 film for covering the entire substrate was understood and demonstrated.