Transport properties of SrCe0.95Y0.05O3−δ and its application for hydrogen separation

Abstract Transport properties of SrCe0.95Y0.05O3−δ were studied by impedance spectroscopy and by measuring open-cell voltage (OCV) and gas permeation. Ionic transference numbers were determined by measuring the OCV of concentration cells and water vapor evolution of an O2/H2 fuel cell. We observed interfacial polarization on the basis of the I–V curves obtained by discharging a hydrogen concentration cell or an O2/H2 fuel cell. The observed high protonic conductivity (high proton and low oxide ion transference numbers) makes SrCe0.95Y0.05O3−δ a potential material for hydrogen separation. From proton conductivity measurements, under a given hydrogen partial pressure difference of 4%/0.488%, the hydrogen permeation rate (of a dense membrane with 0.11 cm in thickness) was calculated to be ≈0.072 cm3 (STP) cm−2 min−1 at 800°C, whereas the permeation rate calculated from short-circuit current measurements was ≈0.023 cm3 (STP) cm−2 min−1 at 800°C. The difference between calculated and observed permeation rates is probably due to interfacial polarization.