A mixed proton-electron conducting ceramic is a metallic oxide having a perovskite type structure, includes at least one member selected from the group consisting of chromium (Cr) , manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and ruthenium (Ru) in ...

A porous catalyst layer containing mixed conducting oxide is contiguous to a second surface (1a) of a selective oxygen-permeable dense continuous layer (1) containing mixed conducting oxide. A porous intermediate catalyst layer (3) containing mixed conduct...