•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.To promote the oxygen permeability of Ba0.5Sr0.5Co0.8Fe0.2O3-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.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.Download high-res image (133KB)Download full-size image

•EDTA–citric (EC) method was first exploited to synthesis nanosized Y0.5Ca0.5BaCo4−xZnxO7 (x = 0.3, 1.0, 1.5) powders.•The Y0.5Ca0.5BaCo4−xZnxO7 materials have relatively low TECs and are chemical stable with SDC electrolytes.•Y0.5Ca0.5BaCo4−xZnxO7-SDC composites were first evaluated as cathode materials for IT-SOFC.•Single cell with the composite cathode and SDC electrolyte has a power density of about 320 mW cm−2 at 700 °C.This paper investigates Y0.5Ca0.5BaCo4−xZnxO7-Ce0.8Sm0.2O2 (SDC) composite cathode materials for intermediate temperature solid oxide fuel cells (SOFCs). The effects of Zn contents in Y0.5Ca0.5BaCo4−xZnxO7 materials on the electrical conductivity, electrochemical performances and thermal expansion have been systemically studied. It is found that the Y0.5Ca0.5BaCo4−xZnxO7 materials have good electrical conductivity. Sintered Y0.5Ca0.5BaCo3ZnO7 samples show a lowest thermal expansion coefficient (TEC) of about 9.3 × 10−6 K−1. This makes the cathode materials well thermally compatible with SDC electrolytes. XRD results show that the Y0.5Ca0.5BaCo4−xZnxO7 materials are chemically stable to SDC electrolyte. Furthermore, Y0.5Ca0.5BaCo4−xZnxO7-SDC composite cathodes have small area specific resistance (ASR) with SDC electrolyte. The ASR value is 0.05 Ω cm2 at 800 °C and 0.11 Ω cm2 at 750 °C, respectively. Single solid oxide fuel cells based on the Y0.5Ca0.5BaCo3ZnO7-SDC (50:50) composite cathode with SDC as electrolyte and Ni/SDC as anode show maximum power density of 320 mW cm−2, 260 mW cm−2 and 200 mW cm−2 at 700 °C, 650 °C and 600 °C, respectively.