Pilhas a combustível de peróxido de hidrogênio direto: efeito do molibdênio em cátodos a base de perovskitas

Abstract

Fuel cells are devices that directly convert chemical energy, between a fuel and an oxidizer, into electrical energy and heat. In the application of this technology, renewable biofuels are used and often oxygen as an oxidizer. However, the use of oxygen can be difficult in some environments, due to the need for storage, and in these cases, hydrogen peroxide can be used. This work studies the use of hydrogen peroxide, as it has a more simplified storage and can be used as an oxidizer, and in some cases, as a fuel. The configuration used is the direct liquid fuel cell type, PCLD, and operates at lower temperatures. In this work, modifications were made to the cathode of the direct hydrogen peroxide cell, in basic medium, in order to improve its performance. For this, the influence of mixed oxides of molybdenum with strontium and lanthanum was evaluated, together with the perovskite lanthanum manganite doped with strontium, LSM, on the reduction reaction of hydrogen peroxide, RRPH, at a temperature between 30° and 35° C. Electrodes supported on carbon fabric, with and without the presence of molybdenum, were produced, which were characterized according to their physical and electrochemical characteristics, by microscopy, profilography, X-ray diffraction, scanning electron volametry, dispersive ray-ray spectroscopy. X and electrochemical impedance. A complete and resistant coating to electrochemical measurements was observed in all samples, and a positive influence of the molybdenum oxides, in the electrochemical performance, for the hydrogen peroxide reduction reaction, when compared with the oxides without molybdenum, presenting current density 32% larger, an electrically active area about 43% larger, and a slight improvement in direct hydrogen peroxide stack power.