Binary-halogen doped BSCF oxide provides a highly oxygen permeable membrane

Oxygen permeability is the primary requirement for mixed ionic electronic conductor (MIEC) membranes. Halogen doping enhances the permeability of MIEC membranes. Various halogens (F, Cl, and I) affect the performance of perovskite oxides differently, owing to variations in electronegativity, ionic radius, and other properties. In this work, an F and Cl co-doping strategy was proposed to improve perovskite oxygen permeation. A series of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δCl_xF_0.1-x materials were synthesized by the solid phase reaction method, and the impact of binary halogen doping on the crystal structure and oxygen permeability performance was systematically studied. Oxygen permeability tests suggested that the Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δCl_0.06F_0.04 disk membrane had good performance of 2.95 ± 0.046 mL min⁻¹·cm⁻², confirming the benefits of the binary halogen-doped strategy. This improved performance results from the F and Cl co-doping, which enhances the oxygen vacancy concentration compared to Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ materials, lowers the average metal-oxygen bond energy, and increases electrical conductivity. These results suggest that the binary halogen-doping strategy offers significant progress in the development of high-performance MIEC materials and potentially provides a new basis for the application of MIEC membranes.