Substantial Oxygen Flux in Fluorite-Rich Dual-Phase Membrane By Tailoring the Surface

Abstract

The oxygen permeation flux of dual-phase doped ceria membranes, Ce0.9Gd0.1O2−δ–La0.7Sr0.3MnO3±δ (GDC/LSM), has been systematically studied as a function of their LSM content, thickness, and coating material. The percolation threshold of the composites for electronic conduction has been determined by general effective-medium theory. The minimum LSM content of the composite for electrical percolation was estimated to be ~20 vol%. The oxygen flux of uncoated fluorite phase-rich membrane exhibits a low oxygen flux under an air/He gradient, indicating that the permeation is mainly controlled by the surface-exchange kinetics of GDC. However, with modification of the surface on both sides, the flux of the membrane was substantially improved by about three orders of magnitude compared with that of the membrane with non-modified surfaces. This observation indicates that the surface modification of fluorite-rich dual phase membrane plays a crucial role in dramatically enhanced oxygen permeation flux. This significant enhancement of the oxygen fluxes is of particular importance as dual-phase membranes are the most studied class of the chemically and mechanically stable membrane. These promising results highlight the potential of dual-phase ceria/pure-electronic-phase membranes for industrial applications.