Investigation of electrocatalytic activity of platinum, tin and ruthenium based electrodes prepared by the Pechini method for the electrooxidation of small organic molecules

Author(s)

Luciene Paula Roberto Profeti

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2004-07-28

Examining board members

Paulo Olivi; Ernesto Rafael Gonzalez; Fritz Cavalcante Huguenin; Marcelo Linardi; Germano Tremiliosi Filho

• Advisor: Paulo Olivi

Abstract

In this work we prepared electrodes containing Pt, Ru and Sn on the Ti substrate by thermal decomposition of polymeric precursors. This method yielded homogeneous films with controlled stoichiometry. The parameters of the preparation process like temperature and oxide composition were investigated. The structural and morphological material characterization were performed by X-ray Diffractometry and Scanning Electronic Microscopy. The electrocatalytic activity was investigated by Cyclic Voltammetry, Chronopotentiometry, in situ Infra-Red Spectroscopy and Fuel Cell tests. The obtained results showed that the preparation method lead to electrodes with a high surface area due to the formation of a cracked and porous morphology. The electrodes containing Ru, Sn and Pt presented the higher catalytic efficiency for the oxidation of small organic molecules than the electrodes of pure platinum. The FTIR spectra allow us to observe the formation of adsorbed CO species in potentials from 0.1 V vs RHE potential values and CO2 for potentials ranging from 0.4 V vs RHE. These values are lower than the expected for pure Pt and confirm the role of Ru in the oxidation of strongly adsorbed intermediates. In the Fuel Cell tests, it were prepared two types of catalysts (carbon supported and non supported catalysts). The carbon supported catalysts presented higher power density than the non-supported catalysts. The electrodes containing 60 % mol of Pt showed the high performance which confirms the results obtained in half cell experiments. The employed preparation method permitted the synthesis of materials that presented good possibilities for the application in Direct Methanol Fuel Cells. (AU)