Oscilações de Voltagem em Células a Combustível de Membrana de Troca Protônica com Ânodos de Pd-Pt/C e Pd/C

Polymer electrolyte membrane fuel cells(PEMFC)showlarge losses by activation when fed with H2contaminated with CO.1Strategies inspired by the use of a second metal in Pt-based anode catalysts have been explored as potential routes to improvethe CO tolerance.2In addition to the greater CO tolerance, bimetallic catalysts may facilitate the emergence of oscillatory instabilities in fuel cells.3Here we report on experimental studies of potential oscillations that emerge in a PEMFC with the Pd/C or PdPt/C anode fed with H2/100 ppm CO mixtures. We have used on linemass spectrometry to investigate the CO2production and CO consumption during potential oscillations. In both cases, our experiments reveal the occurrence of autonomous potential oscillations. Furthermore, we find that the potential oscillations are in phase with the oscillations in CO oxidation and thus of CO2production. This fact is consistent with an autonomous adsorption-oxidation cyclic process.