Effects of surface modification with Co₃O₄ nanoparticles on the oxygen permeability of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ membranes

Graphical abstract: The Co₃O₄ nanoparticles were successfully loaded on to the surfaces of BSCF oxygen permeable membranes by a dip-coating process, which effectively improve the oxygen permeability of membranes. - Highlights: • Co₃O₄ nanoparticles were loaded onto the surface of BSCF membranes by a dip-coating process. • Oxygen permeation flux of the modified BSCF membranes is 4 times higher than the unmodified membranes. • Co₃O₄ modification significantly reduces the oxygen permeation activation energy of the BSCF membranes. - Abstract: To promote the oxygen permeability of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) membranes, Co₃O₄ nanoparticle catalysts were loaded onto the surfaces of BSCF membranes by a dip-coating process. X-ray diffraction (XRD) results reveal that Co₃O₄ nanoparticles crystalize in spinel phase. Scanning electron microscope (SEM) observation indicates that the mean particle size of the Co₃O₄ nanoparticles is about 100 nm in diameter and 20 μm in thickness after annealing at 500 °C for 5 h. Energy dispersive spectrometer (EDS) results testify that the percentage of the elements in the modified layer are in accordance with the stoichiometric ratio of Co₃O₄. Oxygen permeation tests were made in a laboratory self-made device, and the results show that loading Co₃O₄ nanoparticle catalysts onto the surfaces of BSCF membranes can significantly increase the oxygen permeability of the BSCF membranes. The unmodified BSCF membranes have an oxygen permeation flux of 0.1080 ml cm⁻² min⁻¹ at 600 °C. This increases to 0.4302 ml cm⁻² min⁻¹, for the modified membranes, which is four times higher than that of the unmodified BSCF membranes. The oxygen permeation activation energy decreases from 91.42 to 50.71 kJ mol⁻¹ at 600–800 °C by loading Co₃O₄ nanoparticle catalysts on the surface of BSCF membranes.