Tuning the two phases ratio by nonmetal ion doping in dual‐phase mixed‐conductive ceramic membranes

Abstract The mixed protonic–electronic conductor of BaCe 0.5 Fe 0.5 O 3− δ can be automatically decomposed into a dual‐phase material of the cerium‐rich oxide BaCe 0.85 Fe 0.15 O 3− δ (BCFe8515) and the iron‐rich oxide BaCe 0.15 Fe 0.85 O 3− δ (BCFe1585). The BaCe 0.5 Fe 0.5 O 3− δ membrane possessed an extremely high hydrogen (H 2 ) permeation flux, but poor stability. Therefore, in this work, for the first time, the nonmetal P is doped to increase the proportion of the BaCe 0.85 Fe 0.15 O 3− δ (P‐doped Ce‐rich) phase to improve the stability of the dual‐phase membrane. The developed dual‐phasic ceramic membranes of BaCe 0.5 Fe 0.5− x P x O 3− δ (BCFeP x ) ( x = 0, 0.025, 0.05, 0.1) exhibit enhanced stability compared to their parent oxides. Under the condition of 950°C, feed gas with dry 50% H 2 ‐50% He and sweep gas with wet Ar, the H 2 permeation flux of BCFeP 0.05 membrane stabilized at 1.56 mL min −1 cm −2 after the long‐term stability test for 480 h. The enhanced stability resulted from the increase of the P‐doped Ce‐rich phase content and the inhibition of Fe 2 O 3 phase precipitation from the BaCe 0.15 Fe 0.85 O 3− δ (P‐doped Fe‐rich) phase in the reducing atmosphere by doping non‐metal P element.