Progress in Ce0.8Gd0.2O2−δ protective layers for improving the CO2 stability of Ba0.5Sr0.5Co0.8Fe0.2O3−δ O2-transport membranes†
Ce0.8Gd0.2O2−δ (CGO) thin films were deposited by radio frequency (RF) magnetron sputtering and deposition temperature was changed in order to optimize the microstructure and transport properties of the obtained films. Afterwards, the films were deposited on Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) oxygen separation membranes as CO2 protective layers. Oxygen permeation was finally measured by sweeping both Ar and CO2, and the obtained results were compared with the bare BSCF membrane. It was found that the oxygen permeation of the BSCF is improved by this CGO layer, with a 4-fold improvement in the oxygen permeation flux when using pure CO2 as the sweep gas at 900 °C. Therefore, these CGO protective layers are a promising way for overcoming the limitations of BSCF membranes in CO2-containing environments, associated with surface competitive O2–CO2 adsorption and carbonation of Ba at low temperatures.