Suspension Plasma Sprayed Sr₂Fe_1.4Mo_0.6O_6−δ Electrodes for Solid Oxide Fuel Cells

In this study, suspension plasma spraying (SPS) was applied to deposit double perovskite Sr₂Fe_1.4Mo_0.6O_6−δ (SFM) which can be used as both cathode and anode for solid oxide fuel cells. The effects of SFM concentration on the electrode phase composition, microstructure, and catalytic performance were investigated. The electrodes showed a dense structure when it was deposited at a concentration of 0.05 mol/L. The cathode performance was limited by the limited three-phase boundaries and poor gas diffusion. At 750 °C, cathode polarization (R_pc) was 0.19 Ω cm². When the SFM concentration increased to 0.075 mol/L, the deposits revealed a porous microstructure with well-bonded fine particles. As a result, the R_pc decreased significantly to 0.078 Ω cm² at 750 °C. However, when the SFM concentration was further increased to 0.1 mol/L, the R_pc increased owing to the limited interface bonding between the non-molten particles. As a result, it was found that the SFM suspension concentration should be optimized to achieve a highly active SFM by SPS process. Moreover, when the optimized deposit was employed as an anode and tested in a hydrogen atmosphere, it showed anode polarization resistance (R_pa) of 1.5 Ω cm² at 750 °C.