Abstract
The microwave plasma technique opens a new route for interface engineering by avoiding the formation of insulating phases that were previously considered incompatible via conventional thermal treatment in the furnace. This work shows that perovskite SrCo0.4Fe0.5W0.1O3-δ (SCFW) can be assembled onto the zirconia-based electrolyte within 20 min and shows two orders of magnitude improvement of activity to reduce oxygen as compared to the equivalent prepared via the conventional method.
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Mixed electronic and ionic conductivity (MIEC) perovskite oxides hold promise as cathode with high oxygen reduction reaction (ORR) activity for solid oxide fuel cells (SOFCs) operating at reduced temperatures. However, these MIEC cathodes usually contain lanthanide or alkaline-earth elements at A-site. These elements tend to interact with yttria-stabilized zirconia electrolyte (YSZ) to form unwanted phases such as La2Zr2O7 and SrZrO3 at conventional electrode fabrication conditions (>800 °C). Such unwanted interfacial reaction severely degrades the cell performance. We present a new method to assemble SrCo0.4Fe0.5W0.1O3-δ (SCFW) directly onto YSZ by a highly efficient microwave plasma technique. Intimate contact between SCFW and YSZ phases can be achieved by ten-minute microwave-plasma treatment with no new phase formation. Consequently, the microwave-plasma fabricated interface exhibits a notably high ORR performance, showing an area-specific resistances of 0.11 Ω cm2 at 600 °C, about two orders of magnitude better than the equivalent prepared via the conventional method. Our method is also effective in assembling other MIEC perovskite cathodes such as SrCo0.5Fe0.5O3-δ and SrCo0.8Nb0.1Ta0.1O3-δ on YSZ electrolyte, achieving notable enhancement of the cathode performance. This study thus provides an effective and convenient method for synthesizing reactive and robust interfaces between two incompatible phases with minimized interphase interactions.