Abstract
Impurities on the surface of SOFC electrodes can dramatically reduce their interfacial transport. In this work, we use a novel in situ optical absorption relaxation technique to derive the oxygen exchange rate in the absence of electrodes, thereby studying the "innate" material. Si is found to be an impurity in high concentration, with its presence associated with an orders of magnitude decrease in oxygen exchange rate. Addition of La to the electrode surface is found to substantially improve oxygen exchange rate.