Corn-cob like nanofibres as cathode catalysts for an effective microstructure design in solid oxide fuel cells

An efficient cathode for solid oxide fuel cells (SOFC) is mainly determined by the oxygen reduction reaction (ORR) activity of mixed materials. We demonstrate a new microstructure design through a nanofibrous electrode based on a unique corn-cob structure. A one-step process to produce corn-cob ceramic nanofibers of La_0.8Sr_0.2MnO₃ (LSM) and Y₂O₃-stabilized ZrO₂ (YSZ) is introduced using an electrospinning system equipped with a coaxial nozzle. From the microscope analysis, perfect corn-cob nanofibers are finely produced with a diameter of 350 nm for the core and nanoparticles (30-40 nm) stacked on the surface similar to a core-shell structure. The cathode fabricated using nanofibers with LSM outside and YSZ inside (YSZ@LSM) shows the best maximum power density of 1.15 W cm^-2 at 800 °C with low polarization resistance, which is higher than that of the reverse core and shell positions (LSM@YSZ) and even the commercial LSM-YSZ. This better outcome is more prominent at elevated temperatures due to its accelerated catalytic activity. Therefore, insight into the key factors that enhance ORR activity and single cell performance is obtained in terms of not only the nanofibrous core@shell structure but also more reaction active sites from the optimum catalyst position at the designed corn-cob nanofiber based cathodes.