Planar sandwich‐structured dual‐phase composite membrane enables high oxygen permeation and enhanced robustness

Abstract Mixed ionic‐electronic conducting ceramic membranes offer significant potential for oxygen separation from air. This study aimed to enhance both oxygen permeation performance and structural robustness of the ceramic membranes by designing a novel architecture: a thin, dense functional layer sandwiched between thick, finger‐like porous support layers. A planar Gd 0.2 Ce 0.8 O 2− δ (GDC)–La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF) (mass ratio 70:30) composite membrane was fabricated free of warpage and cracks via phase‐inversion tape casting, lamination, and co‐sintering, followed by modification with SrCo 0.1 Fe 0.8 Nb 0.1 O 3− δ (SCFN) nanoparticles via impregnation. When one side of the membrane was exposed to ambient air and the opposite side was swept with helium, a high oxygen permeation flux of 3.19 mL (STP) cm −2 min −1 was achieved at 900°C. This outstanding performance originated from the concurrent optimization of three rate‐limiting processes: SCFN nanoparticles enhanced surface exchange kinetics, a thin dense layer minimized ionic/electronic transport resistance, and finger‐like pores enabled rapid gas‐phase mass transport. Furthermore, the membrane demonstrated outstanding stability, maintaining a constant flux for over 85 h at 900°C and withstanding 42 thermal cycles between 700 and 900°C. The robust ceramic membrane developed in this work is promising for efficient oxygen production from air.