Turning A-site deficient concentration of (Ba_0.5Sr_0.5)_1-xCo_0.7Fe_0.2Ni_0.1O_3-δ perovskite membrane for oxygen separation

The A-site deficient perovskites bring more space for materials design and surface engineering in many fields. In this work, a series of (Ba_0.5Sr_0.5)_1-xCo_0.7Fe_0.2Ni_0.1O_3-δ (BSCFN) membranes with Ni-substitution and different A-site deficient concentrations were designed to improve the oxygen permeability. The influence of A-site deficient concentration and sintered temperature on the microstructure, oxygen permeability, and stability of BSCFN were investigated. The results show that NiO aggregation happens on the membrane surface which surprisingly accelerates the surface exchange reactions of oxygen. Among the series of BSCFN membranes, BSCFN-2–1140 exhibits the highest oxygen permeation flux of 2.36 mL min⁻¹ cm⁻² at 900 °C, which is 1.87 times higher than that of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF). Furthermore, the long-term stability test lasted over 400 h without degradation. Our work demonstrates the feasibility of the A-site deficient strategy and surface nanostructure engineering for oxygen separation and catalytic membrane reactors.