Hydrogen Permeation Properties in (Ce,Sr)PO4

Ceramic membranes of a proton-electron hole mixed conductor, (Ce0.97Sr0.03PO4-delta), were prepared for hydrogen permeation measurements. Hydrogen was found to be considerably permeated with the ambipolar diffusion kinetics through the ceramic membranes. In addition, use of surface catalysts, such as pure platinum, palladium-Ce0.97Sr0.03PO4-delta, and platinum-Ce0.97Sr0.03PO4-delta composites, enhanced the hydrogen permeation flux, suggesting that the contribution of the surface reaction to the hydrogen permeation process is remarkable. The hydrogen permeation flux of (Ce,Sr)PO4 was found to be comparable to or slightly lower than that of perovskite-type mixed conductors of proton and electron holes reported in the preceding works. This paper reports on the hydrogen permeability of ceramic membranes, in which any alkaline earth metals are not included as main components. High chemical stability in atmospheres containing carbon dioxide and water vapor is expected for the class of this material contrary to some perovskite-type mixed proton and electron hole conductors. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3065962] All rights reserved.