Coking resistant Ni–La_0.8Sr_0.2FeO₃ composite anode improves the stability of syngas-fueled SOFC

An improved SOFC anode with excellent stability against carbon deposition with syngas as fuel is reported. The anode material is Ni–La_0.8Sr_0.2FeO₃ (LSF) composite synthesized by anhydrous impregnation. After reduction in wet H₂ (3% H₂O), the material partially decomposes to SrLaFeO₄ and exsolved Fe. The exsolved Fe forms Ni–Fe alloy with impregnated Ni. The particle size of Ni–Fe alloy is about 20–50 nm. The Ni–Fe alloy nanoparticles disperse on the surface of the La_0.8Sr_0.2FeO₃ and SrLaFeO₄ oxides. The increase of Ni content promotes the exsolution of Fe and increases the reaction sites of Ni–Fe alloy. With the increase of the Ni content, the electrical conductivity and catalytic activity are enhanced, which improves the electrochemical performance of the single cell. The cell with 10 mol.% Ni impregnated Ni-LSF as anode achieves a maximum power density of 550 mW cm⁻² at 700 °C fueled with syngas. The strong interaction of the nano-sized Ni–Fe alloy with the La_xSr_yFeO_z (La_0.8Sr_0.2FeO₃ or SrLaFeO₄) oxide substrate efficiently suppresses carbon deposition with high graphitization degree. Besides, the SrLaFeO₄ phase which can accommodate interstitial oxygen facilitates the removal of the deposited carbon.