Desenvolvimento de novos eletrocatalisadores para utilização em eletrodos de células a combustível

Abstract

Fuel cells are the cleanest and most promising form of energy in terms of replacing fossil fuels, given that they can be used anywhere in the world.In this way, the present work aimed at the study of fuel cells of the DAFC (Direct Alcohol Fuel Cell) type, more specifically the fuel cells of the DEFC (Direct Ethanol Fuel Cell) type, which use ethanol as fuel. However, cells powered by ethanol have a slow reaction kinetics because the C-C bond present in the molecule is difficult to be broken and oxidized; therefore, the study of electrocatalysts is necessary, in view of their ability to accelerate the oxidation process of this fuel. Ethanol is a fuel that is favorable for replacing H2, as it is easier to transport and store. In this work, ethanol was used as fuel, so that its electro-oxidation was evaluated using Pt/C, U1 and Pt/C/U1 electrocatalysts.Pt/C was prepared via MAF (Formic Acid Method); the second, being a uranium complex, was obtained through the interaction between a polydentate ligand and the UO3H2 metallic center, and the third was formed by the junction of the metallic catalyst with the U1 complex in the mass proportions: 2:1; 3:1 and 4:1 (Pt/C:U1). As a result, the most efficient catalyst, in terms of current density, was the Pt/C catalyst, but with the premise of reducing the amount of platinum (an economically important factor) in the composition of the hybrid catalyst, the Pt/C/ U1 2:1 metal/complex showed the best performance, because in this ratio the U1 complex acted more effectively through the bifunctional mechanism, decreasing the potentials for the initiation of ethanol oxidation.