Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications

Abstract

The lead ruthenate pyrochlore Pb 2Ru 2O 6,5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photo-electron spectroscopy, X-ray diffraction, cyclic voltammetry, and O 2 reduction and generation kinetic—mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O 2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode The O 2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O 2 reduction performance was also improved.