Synthesis and oxygen permeation properties of Ce_0.8Sm_0.2O_2-d - Sm_1-xSr_xCu_0.2Fe_0.8O_3-d dual-phase ceramic membranes: effect of Strontium contents and Pd coating layer

In this study, the effects of the strontium (x = 0.2–0.7) contents on oxygen permeation properties of 60 wt% Ce_0.8Sm_0.2O_2-d − 40 wt% Sm_0.8Sr_0.2Cu_0.2Fe_0.8O_3-d (SDC-8228) and 60 wt% Ce_0.8Sm_0.2O_2-d − 40 wt% Sm_0.3Sr_0.7Cu_0.2Fe_0.8O_3-d (SDC-3728) dual-phase (DP) ceramic membranes obtained by one-pot synthesis of a pure Ionic Conducting (IC) phase with a Mixed Ionic–Electronic Conducting (MIEC) phase were investigated under different conditions of temperature (800–1000 °C) and CO₂ atmosphere (0–100%). As a result, it was confirmed that the oxygen permeation properties of selected IC/MIEC DP membranes had increased when the Strontium content (Sr_x) of the MIEC phase increased from Sr_{x = 0.2} to Sr_{x = 0.7}. The results showed that the SDC-3728 DP membrane exhibits higher oxygen flux than the SDC-8228 DP membrane. In detail, the oxygen permeation flux reached ∼0.5 mL min⁻¹ cm⁻² at 1000 °C, which was about was one and a half times higher than the SDC-8228 DP membrane. An additional performance improvement was achieved by coating the SDC-3728 DP membrane with a pure Electron Conductor (EC) like Palladium (Pd) by the electroless deposition technique. The oxygen permeation flux of the Pd surface-modified SDC-3728 DP membrane was ∼2.0 mL min⁻¹ cm⁻² in 100% CO₂ at 1000 °C, which was about three times higher than the SDC-8228 DP membrane.