Thermodynamic and SIMS analyses on the role of proton/water in oxygen reduction process and related degradations in solid oxide fuel cells

► Some curious behavior in the electrochemical reaction in doped ceria is discussed. ► A new insight was made on the oxygen flow with and without cathodic polarization. ► For YSZ systems, three phase boundary (TPB) mechanism is confirmed. ► For GDC, almost whole surface of ceria was activated in the oxygen exchange effects. ► Pulverization of Mn-dissoved YSZ and Cr poisoning of LSM cathode were discussed.