Searching for fast oxygen exchange kinetics: (Bi,Sr)(Fe,Co)O3- perovskites

Our interest in the exchange reaction of oxygen between the gas phase and oxides is twofold: (i) to understand the mechanistic details of one of the "simplest" gas-solid reactions which nevertheless exhibits an astonishing complexity in terms of reaction pathways, (ii) to use this knowledge for improving electrochemical devices which rely critically on a fast oxygen incorporation rate such as cathodes for solid oxide fuel cells (SOFC). In order to clarify the reaction mechanisms we combined various experimental techniques with phenomenological as well as ab-initio modelling. In addition to stability issues, SOFC cathode materials should allow for rapid oxygen incorporation on the whole electrode surface area, as well as quick ion transport through the electrode to the electrolyte. In the perovskites of interest the ionic conductivity is enabled by oxygen vacancies.