Effects of surface modification on the oxygen permeation of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane

• Ba0.5Sr0.5Co0.8Fe0.2O3−δBa0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) membrane is prepared by the tape casting method.
• 3.6 times higher oxygen flux is attained by applying the porous BSCF layer.
• 1.1 μm of the 6.5 μm-thick porous layer affects the enhancement of oxygen flux.
• Apparent kchem is enhanced by a factor of 3.1 for the porous-layer coated BSCF.
• Effective thickness of porous layer is estimated by the transmission line model.

The surface of Ba0.5Sr0.5Co0.8Fe0.2O3−δBa0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) membrane was modified by the addition of a porous layer in order to improve the oxygen permeation properties of this material. At 700 °C, the oxygen permeation rate of a 120μm-thick BSCF sample with a 6.5μm-thick porous layer was 3.6 times that of a similar sample with no surface layer. An estimation of the surface area of the applied porous layer indicated that only the 1.1μm of the porous layer nearest the membrane had an effect on the oxygen permeation rate. Weight relaxation was performed at 400 °C to clarify the enhancement of the surface exchange reaction. The chemical surface exchange coefficient (kchemkchem) was 3.1 times larger for the sample with the porous layer coating. The thickness of the porous layer affecting the oxygen permeation rate was estimated by the transmission line model by DchemDchem and kchemkchem.